Re-add kUseGpuInTests flag in WebRTC browser tests.

chrome/browser/media/chrome_webrtc_video_quality_browsertest.cc

 // Copyright 2013 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.
 
 #include "base/base64.h"
 #include "base/command_line.h"
 #include "base/environment.h"
 #include "base/files/file.h"
 #include "base/files/file_util.h"
 #include "base/files/scoped_temp_dir.h"
@@ skipping 98 matching lines @@
 
   void SetUpCommandLine(base::CommandLine* command_line) override {
     // Set up the command line option with the expected file name. We will check
     // its existence in HasAllRequiredResources().
     webrtc_reference_video_y4m_ = test::GetReferenceFilesDir()
         .Append(test_config_.reference_video)
         .AddExtension(test::kY4mFileExtension);
     command_line->AppendSwitchPath(switches::kUseFileForFakeVideoCapture,
                                    webrtc_reference_video_y4m_);
     command_line->AppendSwitch(switches::kUseFakeDeviceForMediaStream);
+
+    // The video playback will not work without a GPU, so force its use here.
+    command_line->AppendSwitch(switches::kUseGpuInTests);
   }
 
   // Writes all frames we've captured so far by grabbing them from the
   // javascript and writing them to the temporary work directory.
   void WriteCapturedFramesToWorkingDir(content::WebContents* capturing_tab) {
     int num_frames = 0;
     std::string response =
         ExecuteJavascript("getTotalNumberCapturedFrames()", capturing_tab);
     ASSERT_TRUE(base::StringToInt(response, &num_frames)) <<
         "Failed to retrieve frame count: got " << response;
@@ skipping 200 matching lines @@
   ASSERT_TRUE(CompareVideosAndPrintResult(
       test_config_.test_name,
       test_config_.width,
       test_config_.height,
       GetWorkingDir().Append(kCapturedYuvFileName),
       test::GetReferenceFilesDir()
           .Append(test_config_.reference_video)
           .AddExtension(test::kYuvFileExtension),
       GetWorkingDir().Append(kStatsFileName)));
 }