Introduce image loading performance test. (#34823)

* Introduce image loading performance test.

This example reports how long it takes to load images over the network(locally spawned server).

dev/devicelab/bin/tasks/image_list_reported_duration.dart

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'dart:async';
+
+import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/utils.dart';
+import 'package:flutter_devicelab/tasks/perf_tests.dart';
+
+Future<void> main() async {
+  await task(ReportedDurationTest(
+    '${flutterDirectory.path}/examples/image_list',
+    'lib/main.dart',
+    'com.example.image_list',
+    RegExp(r'===image_list=== all loaded in ([\d]+)ms.'),
+  ).run);
+}
\ No newline at end of file

dev/devicelab/lib/tasks/perf_tests.dart

@@ -607,6 +607,65 @@ class MemoryTest {
   }
 }
 
+class ReportedDurationTest {
+  ReportedDurationTest(this.project, this.test, this.package, this.durationPattern);
+
+  final String project;
+  final String test;
+  final String package;
+  final RegExp durationPattern;
+
+  final Completer<int> durationCompleter = Completer<int>();
+
+  int get iterationCount => 10;
+
+  Device get device => _device;
+  Device _device;
+
+  Future<TaskResult> run() {
+    return inDirectory<TaskResult>(project, () async {
+      // This test currently only works on Android, because device.logcat,
+      // device.getMemoryStats, etc, aren't implemented for iOS.
+
+      _device = await devices.workingDevice;
+      await device.unlock();
+      await flutter('packages', options: <String>['get']);
+
+      if (deviceOperatingSystem == DeviceOperatingSystem.ios)
+        await prepareProvisioningCertificates(project);
+
+      final StreamSubscription<String> adb = device.logcat.listen(
+        (String data) {
+          if (durationPattern.hasMatch(data))
+            durationCompleter.complete(int.parse(durationPattern.firstMatch(data).group(1)));
+        },
+      );
+      print('launching $project$test on device...');
+      await flutter('run', options: <String>[
+        '--verbose',
+        '--release',
+        '--no-resident',
+        '-d', device.deviceId,
+        test,
+      ]);
+
+      final int duration = await durationCompleter.future;
+      print('terminating...');
+      await device.stop(package);
+      await adb.cancel();
+
+      _device = null;
+
+      final Map<String, dynamic> reportedDuration = <String, dynamic>{
+        'duration': duration
+      };
+      _device = null;
+
+      return TaskResult.success(reportedDuration, benchmarkScoreKeys: reportedDuration.keys.toList());
+    });
+  }
+}
+
 /// Holds simple statistics of an odd-lengthed list of integers.
 class ListStatistics {
   factory ListStatistics(Iterable<int> data) {

dev/devicelab/manifest.yaml

@@ -350,6 +350,12 @@ tasks:
     stage: devicelab
     required_agent_capabilities: ["linux/android"]
 
+  image_list_reported_duration:
+    description: >
+      Measures image loading performance.
+    stage: devicelab
+    required_agent_capabilities: ["linux/android"]
+    flaky: true
 
   # iOS on-device tests
 

examples/image_list/README.md

+# image_list
+
+An example that sets up local http server for serving single
+image, creates single flutter widget with five copies of requested
+image and prints how long the loading took.
+
+This is used in [$FH/flutter/devicelab/bin/tasks/image_list_reported_duration.dart] test.

examples/image_list/android/app/build.gradle

+def localProperties = new Properties()
+def localPropertiesFile = rootProject.file('local.properties')
+if (localPropertiesFile.exists()) {
+    localPropertiesFile.withReader('UTF-8') { reader ->
+        localProperties.load(reader)
+    }
+}
+
+def flutterRoot = localProperties.getProperty('flutter.sdk')
+if (flutterRoot == null) {
+    throw new GradleException("Flutter SDK not found. Define location with flutter.sdk in the local.properties file.")
+}
+
+def flutterVersionCode = localProperties.getProperty('flutter.versionCode')
+if (flutterVersionCode == null) {
+    flutterVersionCode = '1'
+}
+
+def flutterVersionName = localProperties.getProperty('flutter.versionName')
+if (flutterVersionName == null) {
+    flutterVersionName = '1.0'
+}
+
+apply plugin: 'com.android.application'
+apply from: "$flutterRoot/packages/flutter_tools/gradle/flutter.gradle"
+
+android {
+    compileSdkVersion 28
+
+    lintOptions {
+        disable 'InvalidPackage'
+    }
+
+    defaultConfig {
+        // TODO: Specify your own unique Application ID (https://developer.android.com/studio/build/application-id.html).
+        applicationId "com.example.image_list"
+        minSdkVersion 16
+        targetSdkVersion 28
+        versionCode flutterVersionCode.toInteger()
+        versionName flutterVersionName
+        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
+    }
+
+    buildTypes {
+        release {
+            // TODO: Add your own signing config for the release build.
+            // Signing with the debug keys for now, so `flutter run --release` works.
+            signingConfig signingConfigs.debug
+        }
+    }
+}
+
+flutter {
+    source '../..'
+}
+
+dependencies {
+    testImplementation 'junit:junit:4.12'
+    androidTestImplementation 'com.android.support.test:runner:1.0.2'
+    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
+}

examples/image_list/android/app/src/main/AndroidManifest.xml

+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="com.example.image_list">
+
+    <!-- io.flutter.app.FlutterApplication is an android.app.Application that
+         calls FlutterMain.startInitialization(this); in its onCreate method.
+         In most cases you can leave this as-is, but you if you want to provide
+         additional functionality it is fine to subclass or reimplement
+         FlutterApplication and put your custom class here. -->
+    <uses-permission android:name="android.permission.INTERNET" />
+    <application
+        android:name="io.flutter.app.FlutterApplication"
+        android:label="image_list"
+        android:icon="@mipmap/ic_launcher">
+        <activity
+            android:name=".MainActivity"
+            android:launchMode="singleTop"
+            android:theme="@style/LaunchTheme"
+            android:configChanges="orientation|keyboardHidden|keyboard|screenSize|locale|layoutDirection|fontScale|screenLayout|density|uiMode"
+            android:hardwareAccelerated="true"
+            android:windowSoftInputMode="adjustResize">
+            <!-- This keeps the window background of the activity showing
+                 until Flutter renders its first frame. It can be removed if
+                 there is no splash screen (such as the default splash screen
+                 defined in @style/LaunchTheme). -->
+            <meta-data
+                android:name="io.flutter.app.android.SplashScreenUntilFirstFrame"
+                android:value="true" />
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN"/>
+                <category android:name="android.intent.category.LAUNCHER"/>
+            </intent-filter>
+        </activity>
+    </application>
+</manifest>

examples/image_list/android/app/src/main/java/com/example/image_list/MainActivity.java

+package com.example.image_list;
+
+import android.os.Bundle;
+import io.flutter.app.FlutterActivity;
+import io.flutter.plugins.GeneratedPluginRegistrant;
+
+public class MainActivity extends FlutterActivity {
+  @Override
+  protected void onCreate(Bundle savedInstanceState) {
+    super.onCreate(savedInstanceState);
+    GeneratedPluginRegistrant.registerWith(this);
+  }
+}

examples/image_list/android/app/src/main/res/drawable/launch_background.xml

+<?xml version="1.0" encoding="utf-8"?>
+<!-- Modify this file to customize your launch splash screen -->
+<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
+    <item android:drawable="@android:color/white" />
+
+    <!-- You can insert your own image assets here -->
+    <!-- <item>
+        <bitmap
+            android:gravity="center"
+            android:src="@mipmap/launch_image" />
+    </item> -->
+</layer-list>

examples/image_list/android/app/src/main/res/values/styles.xml

+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <style name="LaunchTheme" parent="@android:style/Theme.Black.NoTitleBar">
+        <!-- Show a splash screen on the activity. Automatically removed when
+             Flutter draws its first frame -->
+        <item name="android:windowBackground">@drawable/launch_background</item>
+    </style>
+</resources>

examples/image_list/android/build.gradle

+buildscript {
+    repositories {
+        google()
+        jcenter()
+    }
+
+    dependencies {
+        classpath 'com.android.tools.build:gradle:3.2.1'
+    }
+}
+
+allprojects {
+    repositories {
+        google()
+        jcenter()
+    }
+}
+
+rootProject.buildDir = '../build'
+subprojects {
+    project.buildDir = "${rootProject.buildDir}/${project.name}"
+}
+subprojects {
+    project.evaluationDependsOn(':app')
+}
+
+task clean(type: Delete) {
+    delete rootProject.buildDir
+}

examples/image_list/android/gradle.properties

+org.gradle.jvmargs=-Xmx1536M
+

examples/image_list/android/settings.gradle

+include ':app'
+
+def flutterProjectRoot = rootProject.projectDir.parentFile.toPath()
+
+def plugins = new Properties()
+def pluginsFile = new File(flutterProjectRoot.toFile(), '.flutter-plugins')
+if (pluginsFile.exists()) {
+    pluginsFile.withReader('UTF-8') { reader -> plugins.load(reader) }
+}
+
+plugins.each { name, path ->
+    def pluginDirectory = flutterProjectRoot.resolve(path).resolve('android').toFile()
+    include ":$name"
+    project(":$name").projectDir = pluginDirectory
+}

examples/image_list/ios/Flutter/AppFrameworkInfo.plist

+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+  <key>CFBundleDevelopmentRegion</key>
+  <string>$(DEVELOPMENT_LANGUAGE)</string>
+  <key>CFBundleExecutable</key>
+  <string>App</string>
+  <key>CFBundleIdentifier</key>
+  <string>io.flutter.flutter.app</string>
+  <key>CFBundleInfoDictionaryVersion</key>
+  <string>6.0</string>
+  <key>CFBundleName</key>
+  <string>App</string>
+  <key>CFBundlePackageType</key>
+  <string>FMWK</string>
+  <key>CFBundleShortVersionString</key>
+  <string>1.0</string>
+  <key>CFBundleSignature</key>
+  <string>????</string>
+  <key>CFBundleVersion</key>
+  <string>1.0</string>
+  <key>MinimumOSVersion</key>
+  <string>8.0</string>
+</dict>
+</plist>

examples/image_list/ios/Flutter/Debug.xcconfig

+#include "Generated.xcconfig"

examples/image_list/ios/Flutter/Release.xcconfig

+#include "Generated.xcconfig"

examples/image_list/ios/Runner.xcodeproj/project.xcworkspace/contents.xcworkspacedata

+<?xml version="1.0" encoding="UTF-8"?>
+<Workspace
+   version = "1.0">
+   <FileRef
+      location = "group:Runner.xcodeproj">
+   </FileRef>
+</Workspace>

examples/image_list/ios/Runner.xcodeproj/xcshareddata/xcschemes/Runner.xcscheme

+<?xml version="1.0" encoding="UTF-8"?>
+<Scheme
+   LastUpgradeVersion = "0910"
+   version = "1.3">
+   <BuildAction
+      parallelizeBuildables = "YES"
+      buildImplicitDependencies = "YES">
+      <BuildActionEntries>
+         <BuildActionEntry
+            buildForTesting = "YES"
+            buildForRunning = "YES"
+            buildForProfiling = "YES"
+            buildForArchiving = "YES"
+            buildForAnalyzing = "YES">
+            <BuildableReference
+               BuildableIdentifier = "primary"
+               BlueprintIdentifier = "97C146ED1CF9000F007C117D"
+               BuildableName = "Runner.app"
+               BlueprintName = "Runner"
+               ReferencedContainer = "container:Runner.xcodeproj">
+            </BuildableReference>
+         </BuildActionEntry>
+      </BuildActionEntries>
+   </BuildAction>
+   <TestAction
+      buildConfiguration = "Debug"
+      selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
+      selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
+      language = ""
+      shouldUseLaunchSchemeArgsEnv = "YES">
+      <Testables>
+      </Testables>
+      <MacroExpansion>
+         <BuildableReference
+            BuildableIdentifier = "primary"
+            BlueprintIdentifier = "97C146ED1CF9000F007C117D"
+            BuildableName = "Runner.app"
+            BlueprintName = "Runner"
+            ReferencedContainer = "container:Runner.xcodeproj">
+         </BuildableReference>
+      </MacroExpansion>
+      <AdditionalOptions>
+      </AdditionalOptions>
+   </TestAction>
+   <LaunchAction
+      buildConfiguration = "Debug"
+      selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
+      selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
+      language = ""
+      launchStyle = "0"
+      useCustomWorkingDirectory = "NO"
+      ignoresPersistentStateOnLaunch = "NO"
+      debugDocumentVersioning = "YES"
+      debugServiceExtension = "internal"
+      allowLocationSimulation = "YES">
+      <BuildableProductRunnable
+         runnableDebuggingMode = "0">
+         <BuildableReference
+            BuildableIdentifier = "primary"
+            BlueprintIdentifier = "97C146ED1CF9000F007C117D"
+            BuildableName = "Runner.app"
+            BlueprintName = "Runner"
+            ReferencedContainer = "container:Runner.xcodeproj">
+         </BuildableReference>
+      </BuildableProductRunnable>
+      <AdditionalOptions>
+      </AdditionalOptions>
+   </LaunchAction>
+   <ProfileAction
+      buildConfiguration = "Profile"
+      shouldUseLaunchSchemeArgsEnv = "YES"
+      savedToolIdentifier = ""
+      useCustomWorkingDirectory = "NO"
+      debugDocumentVersioning = "YES">
+      <BuildableProductRunnable
+         runnableDebuggingMode = "0">
+         <BuildableReference
+            BuildableIdentifier = "primary"
+            BlueprintIdentifier = "97C146ED1CF9000F007C117D"
+            BuildableName = "Runner.app"
+            BlueprintName = "Runner"
+            ReferencedContainer = "container:Runner.xcodeproj">
+         </BuildableReference>
+      </BuildableProductRunnable>
+   </ProfileAction>
+   <AnalyzeAction
+      buildConfiguration = "Debug">
+   </AnalyzeAction>
+   <ArchiveAction
+      buildConfiguration = "Release"
+      revealArchiveInOrganizer = "YES">
+   </ArchiveAction>
+</Scheme>

examples/image_list/ios/Runner.xcworkspace/contents.xcworkspacedata

+<?xml version="1.0" encoding="UTF-8"?>
+<Workspace
+   version = "1.0">
+   <FileRef
+      location = "group:Runner.xcodeproj">
+   </FileRef>
+</Workspace>

examples/image_list/ios/Runner/AppDelegate.h

+#import <Flutter/Flutter.h>
+#import <UIKit/UIKit.h>
+
+@interface AppDelegate : FlutterAppDelegate
+
+@end

examples/image_list/ios/Runner/AppDelegate.m

+#include "AppDelegate.h"
+#include "GeneratedPluginRegistrant.h"
+
+@implementation AppDelegate
+
+- (BOOL)application:(UIApplication *)application
+    didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
+  [GeneratedPluginRegistrant registerWithRegistry:self];
+  // Override point for customization after application launch.
+  return [super application:application didFinishLaunchingWithOptions:launchOptions];
+}
+
+@end

examples/image_list/ios/Runner/Assets.xcassets/AppIcon.appiconset/Contents.json

+{
+  "images" : [
+    {
+      "size" : "20x20",
+      "idiom" : "iphone",
+      "filename" : "Icon-App-20x20@2x.png",
+      "scale" : "2x"
+    },
+    {
+      "size" : "20x20",
+      "idiom" : "iphone",
+      "filename" : "Icon-App-20x20@3x.png",
+      "scale" : "3x"
+    },
+    {
+      "size" : "29x29",
+      "idiom" : "iphone",
+      "filename" : "Icon-App-29x29@1x.png",
+      "scale" : "1x"
+    },
+    {
+      "size" : "29x29",
+      "idiom" : "iphone",
+      "filename" : "Icon-App-29x29@2x.png",
+      "scale" : "2x"
+    },
+    {
+      "size" : "29x29",
+      "idiom" : "iphone",
+      "filename" : "Icon-App-29x29@3x.png",
+      "scale" : "3x"
+    },
+    {
+      "size" : "40x40",
+      "idiom" : "iphone",
+      "filename" : "Icon-App-40x40@2x.png",
+      "scale" : "2x"
+    },
+    {
+      "size" : "40x40",
+      "idiom" : "iphone",
+      "filename" : "Icon-App-40x40@3x.png",
+      "scale" : "3x"
+    },
+    {
+      "size" : "60x60",
+      "idiom" : "iphone",
+      "filename" : "Icon-App-60x60@2x.png",
+      "scale" : "2x"
+    },
+    {
+      "size" : "60x60",
+      "idiom" : "iphone",
+      "filename" : "Icon-App-60x60@3x.png",
+      "scale" : "3x"
+    },
+    {
+      "size" : "20x20",
+      "idiom" : "ipad",
+      "filename" : "Icon-App-20x20@1x.png",
+      "scale" : "1x"
+    },
+    {
+      "size" : "20x20",
+      "idiom" : "ipad",
+      "filename" : "Icon-App-20x20@2x.png",
+      "scale" : "2x"
+    },
+    {
+      "size" : "29x29",
+      "idiom" : "ipad",
+      "filename" : "Icon-App-29x29@1x.png",
+      "scale" : "1x"
+    },
+    {
+      "size" : "29x29",
+      "idiom" : "ipad",
+      "filename" : "Icon-App-29x29@2x.png",
+      "scale" : "2x"
+    },
+    {
+      "size" : "40x40",
+      "idiom" : "ipad",
+      "filename" : "Icon-App-40x40@1x.png",
+      "scale" : "1x"
+    },
+    {
+      "size" : "40x40",
+      "idiom" : "ipad",
+      "filename" : "Icon-App-40x40@2x.png",
+      "scale" : "2x"
+    },
+    {
+      "size" : "76x76",
+      "idiom" : "ipad",
+      "filename" : "Icon-App-76x76@1x.png",
+      "scale" : "1x"
+    },
+    {
+      "size" : "76x76",
+      "idiom" : "ipad",
+      "filename" : "Icon-App-76x76@2x.png",
+      "scale" : "2x"
+    },
+    {
+      "size" : "83.5x83.5",
+      "idiom" : "ipad",
+      "filename" : "Icon-App-83.5x83.5@2x.png",
+      "scale" : "2x"
+    },
+    {
+      "size" : "1024x1024",
+      "idiom" : "ios-marketing",
+      "filename" : "Icon-App-1024x1024@1x.png",
+      "scale" : "1x"
+    }
+  ],
+  "info" : {
+    "version" : 1,
+    "author" : "xcode"
+  }
+}

examples/image_list/ios/Runner/Assets.xcassets/LaunchImage.imageset/Contents.json

+{
+  "images" : [
+    {
+      "idiom" : "universal",
+      "filename" : "LaunchImage.png",
+      "scale" : "1x"
+    },
+    {
+      "idiom" : "universal",
+      "filename" : "LaunchImage@2x.png",
+      "scale" : "2x"
+    },
+    {
+      "idiom" : "universal",
+      "filename" : "LaunchImage@3x.png",
+      "scale" : "3x"
+    }
+  ],
+  "info" : {
+    "version" : 1,
+    "author" : "xcode"
+  }
+}

examples/image_list/ios/Runner/Assets.xcassets/LaunchImage.imageset/README.md

+# Launch Screen Assets
+
+You can customize the launch screen with your own desired assets by replacing the image files in this directory.
+
+You can also do it by opening your Flutter project's Xcode project with `open ios/Runner.xcworkspace`, selecting `Runner/Assets.xcassets` in the Project Navigator and dropping in the desired images.
\ No newline at end of file

examples/image_list/ios/Runner/Base.lproj/LaunchScreen.storyboard

+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<document type="com.apple.InterfaceBuilder3.CocoaTouch.Storyboard.XIB" version="3.0" toolsVersion="12121" systemVersion="16G29" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" launchScreen="YES" colorMatched="YES" initialViewController="01J-lp-oVM">
+    <dependencies>
+        <deployment identifier="iOS"/>
+        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="12089"/>
+    </dependencies>
+    <scenes>
+        <!--View Controller-->
+        <scene sceneID="EHf-IW-A2E">
+            <objects>
+                <viewController id="01J-lp-oVM" sceneMemberID="viewController">
+                    <layoutGuides>
+                        <viewControllerLayoutGuide type="top" id="Ydg-fD-yQy"/>
+                        <viewControllerLayoutGuide type="bottom" id="xbc-2k-c8Z"/>
+                    </layoutGuides>
+                    <view key="view" contentMode="scaleToFill" id="Ze5-6b-2t3">
+                        <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
+                        <subviews>
+                            <imageView opaque="NO" clipsSubviews="YES" multipleTouchEnabled="YES" contentMode="center" image="LaunchImage" translatesAutoresizingMaskIntoConstraints="NO" id="YRO-k0-Ey4">
+                            </imageView>
+                        </subviews>
+                        <color key="backgroundColor" red="1" green="1" blue="1" alpha="1" colorSpace="custom" customColorSpace="sRGB"/>
+                        <constraints>
+                            <constraint firstItem="YRO-k0-Ey4" firstAttribute="centerX" secondItem="Ze5-6b-2t3" secondAttribute="centerX" id="1a2-6s-vTC"/>
+                            <constraint firstItem="YRO-k0-Ey4" firstAttribute="centerY" secondItem="Ze5-6b-2t3" secondAttribute="centerY" id="4X2-HB-R7a"/>
+                        </constraints>
+                    </view>
+                </viewController>
+                <placeholder placeholderIdentifier="IBFirstResponder" id="iYj-Kq-Ea1" userLabel="First Responder" sceneMemberID="firstResponder"/>
+            </objects>
+            <point key="canvasLocation" x="53" y="375"/>
+        </scene>
+    </scenes>
+    <resources>
+        <image name="LaunchImage" width="168" height="185"/>
+    </resources>
+</document>

examples/image_list/ios/Runner/Base.lproj/Main.storyboard

+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<document type="com.apple.InterfaceBuilder3.CocoaTouch.Storyboard.XIB" version="3.0" toolsVersion="10117" systemVersion="15F34" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" useTraitCollections="YES" initialViewController="BYZ-38-t0r">
+    <dependencies>
+        <deployment identifier="iOS"/>
+        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="10085"/>
+    </dependencies>
+    <scenes>
+        <!--Flutter View Controller-->
+        <scene sceneID="tne-QT-ifu">
+            <objects>
+                <viewController id="BYZ-38-t0r" customClass="FlutterViewController" sceneMemberID="viewController">
+                    <layoutGuides>
+                        <viewControllerLayoutGuide type="top" id="y3c-jy-aDJ"/>
+                        <viewControllerLayoutGuide type="bottom" id="wfy-db-euE"/>
+                    </layoutGuides>
+                    <view key="view" contentMode="scaleToFill" id="8bC-Xf-vdC">
+                        <rect key="frame" x="0.0" y="0.0" width="600" height="600"/>
+                        <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
+                        <color key="backgroundColor" white="1" alpha="1" colorSpace="custom" customColorSpace="calibratedWhite"/>
+                    </view>
+                </viewController>
+                <placeholder placeholderIdentifier="IBFirstResponder" id="dkx-z0-nzr" sceneMemberID="firstResponder"/>
+            </objects>
+        </scene>
+    </scenes>
+</document>

examples/image_list/ios/Runner/Info.plist

+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>CFBundleDevelopmentRegion</key>
+	<string>$(DEVELOPMENT_LANGUAGE)</string>
+	<key>CFBundleExecutable</key>
+	<string>$(EXECUTABLE_NAME)</string>
+	<key>CFBundleIdentifier</key>
+	<string>$(PRODUCT_BUNDLE_IDENTIFIER)</string>
+	<key>CFBundleInfoDictionaryVersion</key>
+	<string>6.0</string>
+	<key>CFBundleName</key>
+	<string>image_list</string>
+	<key>CFBundlePackageType</key>
+	<string>APPL</string>
+	<key>CFBundleShortVersionString</key>
+	<string>$(FLUTTER_BUILD_NAME)</string>
+	<key>CFBundleSignature</key>
+	<string>????</string>
+	<key>CFBundleVersion</key>
+	<string>$(FLUTTER_BUILD_NUMBER)</string>
+	<key>LSRequiresIPhoneOS</key>
+	<true/>
+	<key>UILaunchStoryboardName</key>
+	<string>LaunchScreen</string>
+	<key>UIMainStoryboardFile</key>
+	<string>Main</string>
+	<key>UISupportedInterfaceOrientations</key>
+	<array>
+		<string>UIInterfaceOrientationPortrait</string>
+		<string>UIInterfaceOrientationLandscapeLeft</string>
+		<string>UIInterfaceOrientationLandscapeRight</string>
+	</array>
+	<key>UISupportedInterfaceOrientations~ipad</key>
+	<array>
+		<string>UIInterfaceOrientationPortrait</string>
+		<string>UIInterfaceOrientationPortraitUpsideDown</string>
+		<string>UIInterfaceOrientationLandscapeLeft</string>
+		<string>UIInterfaceOrientationLandscapeRight</string>
+	</array>
+	<key>UIViewControllerBasedStatusBarAppearance</key>
+	<false/>
+</dict>
+</plist>

examples/image_list/ios/Runner/main.m

+#import <Flutter/Flutter.h>
+#import <UIKit/UIKit.h>
+#import "AppDelegate.h"
+
+int main(int argc, char* argv[]) {
+  @autoreleasepool {
+    return UIApplicationMain(argc, argv, nil, NSStringFromClass([AppDelegate class]));
+  }
+}

examples/image_list/lib/main.dart

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'dart:async';
+import 'dart:io';
+import 'dart:typed_data';
+import 'package:flutter/material.dart';
+import 'package:flutter/services.dart' show rootBundle;
+import 'package:flutter/services.dart';
+
+/// An example that sets up local http server for serving single
+/// image, creates single flutter widget with five copies of requested
+/// image and prints how long the loading took.
+///
+/// This is used in [$FH/flutter/devicelab/bin/tasks/image_list_reported_duration.dart] test.
+Future<void> main() async {
+  final HttpServer httpServer =
+      await HttpServer.bind(InternetAddress.anyIPv6, 0);
+  final int port = httpServer.port;
+  print('Listening on port $port.');
+
+  final ByteData byteData = await rootBundle.load('images/coast.jpg');
+  final Uint8List bytes = byteData.buffer
+      .asUint8List(byteData.offsetInBytes, byteData.lengthInBytes);
+  httpServer.listen((HttpRequest request) async {
+    request.response.add(bytes);
+    request.response.close();
+  });
+
+  runApp(MyApp(port));
+}
+
+const int IMAGES = 50;
+
+@immutable
+class MyApp extends StatelessWidget {
+  const MyApp(this.port);
+
+  final int port;
+
+  @override
+  Widget build(BuildContext context) {
+    return MaterialApp(
+      title: 'Flutter Demo',
+      theme: ThemeData(
+        primarySwatch: Colors.blue,
+      ),
+      home: MyHomePage(title: 'Flutter Demo Home Page', port: port),
+    );
+  }
+}
+
+class MyHomePage extends StatefulWidget {
+  const MyHomePage({Key key, this.title, this.port}) : super(key: key);
+  final String title;
+  final int port;
+
+  @override
+  _MyHomePageState createState() => _MyHomePageState();
+}
+
+class _MyHomePageState extends State<MyHomePage> with TickerProviderStateMixin {
+  int _counter = 0;
+
+  void _incrementCounter() {
+    setState(() {
+      _counter++;
+    });
+  }
+
+  Widget createImage(final int index, final Completer<bool> completer) {
+    return Image.network(
+        'http://localhost:${widget.port}/${_counter * IMAGES + index}',
+        frameBuilder: (
+          BuildContext context,
+          Widget child,
+          int frame,
+          bool wasSynchronouslyLoaded,
+        ) {
+          if (frame == 0 && !completer.isCompleted) {
+            completer.complete(true);
+          }
+          return child;
+        },
+    );
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    final List<AnimationController> controllers = List<AnimationController>(IMAGES);
+    for (int i = 0; i < IMAGES; i++) {
+      controllers[i] = AnimationController(
+        duration: const Duration(milliseconds: 3600),
+        vsync: this,
+      )..repeat();
+    }
+    final List<Completer<bool>> completers = List<Completer<bool>>(IMAGES);
+    for (int i = 0; i < IMAGES; i++) {
+      completers[i] = Completer<bool>();
+    }
+    final List<Future<bool>> futures = completers.map(
+        (Completer<bool> completer) => completer.future).toList();
+    final DateTime started = DateTime.now();
+    Future.wait(futures).then((_) {
+      print(
+          '===image_list=== all loaded in ${DateTime.now().difference(started).inMilliseconds}ms.');
+    });
+    return Scaffold(
+      appBar: AppBar(
+        title: Text(widget.title),
+      ),
+      body: Center(
+        child: Column(
+          mainAxisAlignment: MainAxisAlignment.center,
+          children: <Widget>[
+            Row(children: createImageList(IMAGES, completers, controllers)),
+            const Text(
+              'You have pushed the button this many times:',
+            ),
+            Text(
+              '$_counter',
+              style: Theme.of(context).textTheme.display1,
+            ),
+          ],
+        ),
+      ),
+      floatingActionButton: FloatingActionButton(
+        onPressed: _incrementCounter,
+        tooltip: 'Increment',
+        child: Icon(Icons.add),
+      ),
+    );
+  }
+
+  List<Widget> createImageList(int count, List<Completer<bool>> completers,
+      List<AnimationController> controllers) {
+    final List<Widget> list = <Widget>[];
+    for (int i = 0; i < count; i++) {
+      list.add(Flexible(
+          fit: FlexFit.tight,
+          flex: i + 1,
+          child: RotationTransition(
+              turns: controllers[i],
+              child: createImage(i + 1, completers[i]))));
+    }
+    return list;
+  }
+}

examples/image_list/pubspec.yaml

+name: image_list
+description: Simple Flutter project used for benchmarking image loading over network.
+
+version: 1.0.0+1
+
+environment:
+  sdk: ">=2.1.0 <3.0.0"
+
+dependencies:
+  flutter:
+    sdk: flutter
+
+  # The following adds the Cupertino Icons font to your application.
+  # Use with the CupertinoIcons class for iOS style icons.
+  cupertino_icons: 0.1.2
+
+  collection: 1.14.11 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  meta: 1.1.6 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  typed_data: 1.1.6 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  vector_math: 2.0.8 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+
+dev_dependencies:
+  flutter_test:
+    sdk: flutter
+
+# For information on the generic Dart part of this file, see the
+# following page: https://dart.dev/tools/pub/pubspec
+
+# The following section is specific to Flutter.
+
+  async: 2.2.0 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  boolean_selector: 1.0.5 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  charcode: 1.1.2 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  matcher: 0.12.5 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  path: 1.6.2 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  pedantic: 1.7.0 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  quiver: 2.0.3 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  source_span: 1.5.5 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  stack_trace: 1.9.3 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  stream_channel: 2.0.0 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  string_scanner: 1.0.4 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  term_glyph: 1.1.0 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  test_api: 0.2.5 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+
+flutter:
+
+  # The following line ensures that the Material Icons font is
+  # included with your application, so that you can use the icons in
+  # the material Icons class.
+  uses-material-design: true
+
+  # To add assets to your application, add an assets section, like this:
+  assets:
+   - images/coast.jpg
+
+# PUBSPEC CHECKSUM: 9c01