Re-add kUseGpuInTests flag in WebRTC browser tests.

chrome/browser/media/chrome_webrtc_apprtc_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/command_line.h"
 #include "base/files/file_enumerator.h"
 #include "base/path_service.h"
 #include "base/process/launch.h"
 #include "base/rand_util.h"
 #include "base/strings/stringprintf.h"
@@ skipping 37 matching lines @@
 //
 // This test will bring up a AppRTC instance on localhost and verify that the
 // call gets up when connecting to the same room from two tabs in a browser.
 class WebRtcApprtcBrowserTest : public WebRtcTestBase {
  public:
   WebRtcApprtcBrowserTest() {}
 
   void SetUpCommandLine(base::CommandLine* command_line) override {
     EXPECT_FALSE(command_line->HasSwitch(switches::kUseFakeUIForMediaStream));
 
-    // Use fake devices in order to run on VMs.
-    command_line->AppendSwitch(switches::kUseFakeDeviceForMediaStream);
+    // The video playback will not work without a GPU, so force its use here.
+    command_line->AppendSwitch(switches::kUseGpuInTests);
+    base::CommandLine::ForCurrentProcess()->AppendSwitch(
+        switches::kUseFakeDeviceForMediaStream);
   }
 
   void TearDown() override {
     // Kill any processes we may have brought up. Note: this isn't perfect,
     // especially if the test hangs or if we're on Windows.
     LOG(INFO) << "Entering TearDown";
     if (dev_appserver_.IsValid())
       base::KillProcess(dev_appserver_.Handle(), 0, false);
     if (collider_server_.IsValid())
       base::KillProcess(collider_server_.Handle(), 0, false);
@@ skipping 207 matching lines @@
                        "&firefox_fake_device=1");
   content::WebContents* chrome_tab = OpenPageAndAcceptUserMedia(room_url);
 
   ASSERT_TRUE(LaunchFirefoxWithUrl(room_url));
 
   ASSERT_TRUE(WaitForCallToComeUp(chrome_tab));
 
   // Ensure Firefox manages to send video our way.
   ASSERT_TRUE(DetectRemoteVideoPlaying(chrome_tab));
 }