Run pod install in flutter_view_ios__start_up test. (#13296)

dev/devicelab/bin/tasks/flutter_view_ios__start_up.dart

@@ -3,12 +3,20 @@
 // found in the LICENSE file.
 
 import 'dart:async';
+import 'dart:io';
 
+import 'package:flutter_devicelab/framework/utils.dart';
 import 'package:flutter_devicelab/tasks/perf_tests.dart';
 import 'package:flutter_devicelab/framework/adb.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
 
 Future<Null> main() async {
   deviceOperatingSystem = DeviceOperatingSystem.ios;
+  final Directory iosDirectory = dir(
+    '${flutterDirectory.path}/examples/flutter_view/ios',
+  );
+  await inDirectory(iosDirectory, () async {
+    await exec('pod', <String>['install']);
+  });
   await task(createFlutterViewStartupTest());
 }