Minor style tweaks (#9766)

packages/flutter_tools/lib/src/ios/devices.dart

@@ -49,10 +49,11 @@ class IOSDevice extends Device {
     _loggerPath = _checkForCommand('idevicesyslog');
     _screenshotPath = _checkForCommand('idevicescreenshot');
     _pusherPath = _checkForCommand(
-        'ios-deploy',
-        'To copy files to iOS devices, please install ios-deploy. To install, run:\n'
-        'brew update\n'
-        'brew install ios-deploy');
+      'ios-deploy',
+      'To copy files to iOS devices, please install ios-deploy. To install, run:\n'
+      'brew update\n'
+      'brew install ios-deploy'
+    );
   }
 
   String _installerPath;
@@ -162,7 +163,7 @@ class IOSDevice extends Device {
     final IOSApp iosApp = app;
     final Directory bundle = fs.directory(iosApp.deviceBundlePath);
     if (!bundle.existsSync()) {
-      printError("Could not find application bundle at ${bundle.path}; have you run 'flutter build ios'?");
+      printError('Could not find application bundle at ${bundle.path}; have you run "flutter build ios"?');
       return false;
     }
 
@@ -225,16 +226,16 @@ class IOSDevice extends Device {
     }
 
     // Step 3: Attempt to install the application on the device.
-    final List<String> launchArguments = <String>["--enable-dart-profiling"];
+    final List<String> launchArguments = <String>['--enable-dart-profiling'];
 
     if (debuggingOptions.startPaused)
-      launchArguments.add("--start-paused");
+      launchArguments.add('--start-paused');
 
     if (debuggingOptions.useTestFonts)
-      launchArguments.add("--use-test-fonts");
+      launchArguments.add('--use-test-fonts');
 
     if (debuggingOptions.debuggingEnabled) {
-      launchArguments.add("--enable-checked-mode");
+      launchArguments.add('--enable-checked-mode');
 
       // Note: We do NOT need to set the observatory port since this is going to
       // be setup on the device. Let it pick a port automatically. We will check
@@ -266,12 +267,12 @@ class IOSDevice extends Device {
 
     if (!debuggingOptions.debuggingEnabled) {
       // If debugging is not enabled, just launch the application and continue.
-      printTrace("Debugging is not enabled");
+      printTrace('Debugging is not enabled');
       installationResult = await runCommandAndStreamOutput(launchCommand, trace: true);
     } else {
       // Debugging is enabled, look for the observatory and diagnostic server
       // ports post launch.
-      printTrace("Debugging is enabled, connecting to observatory and the diagnostic server");
+      printTrace('Debugging is enabled, connecting to observatory and the diagnostic server');
 
       // TODO(danrubel): The Android device class does something similar to this code below.
       // The various Device subclasses should be refactored and common code moved into the superclass.
@@ -294,11 +295,11 @@ class IOSDevice extends Device {
         installationResult = result;
 
         if (result != 0) {
-          printTrace("Failed to launch the application on device.");
+          printTrace('Failed to launch the application on device.');
           return <Uri>[null, null];
         }
 
-        printTrace("Application launched on the device. Attempting to forward ports.");
+        printTrace('Application launched on the device. Attempting to forward ports.');
         return await Future.wait(<Future<Uri>>[forwardObsUri, forwardDiagUri]);
       }).whenComplete(() {
         observatoryDiscovery.cancel();
@@ -459,7 +460,7 @@ class _IOSDevicePortForwarder extends DevicePortForwarder {
     final ForwardedPort forwardedPort = new ForwardedPort.withContext(hostPort,
         devicePort, process);
 
-    printTrace("Forwarded port $forwardedPort");
+    printTrace('Forwarded port $forwardedPort');
 
     _forwardedPorts.add(forwardedPort);
 
@@ -473,14 +474,14 @@ class _IOSDevicePortForwarder extends DevicePortForwarder {
       return null;
     }
 
-    printTrace("Unforwarding port $forwardedPort");
+    printTrace('Unforwarding port $forwardedPort');
 
     final Process process = forwardedPort.context;
 
     if (process != null) {
       processManager.killPid(process.pid);
     } else {
-      printError("Forwarded port did not have a valid process");
+      printError('Forwarded port did not have a valid process');
     }
 
     return null;