Add flag --require-audio-hardware-for-testing.

media/base/media_switches.cc

 // Copyright (c) 2012 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 "media/base/media_switches.h"
 
 namespace switches {
 
 // Allow users to specify a custom buffer size for debugging purpose.
 const char kAudioBufferSize[] = "audio-buffer-size";
@@ skipping 87 matching lines @@
 // Play a .wav file as the microphone. Note that for WebRTC calls we'll treat
 // the bits as if they came from the microphone, which means you should disable
 // audio processing (lest your audio file will play back distorted). The input
 // file is converted to suit Chrome's audio buses if necessary, so most sane
 // .wav files should work.
 const char kUseFileForFakeAudioCapture[] = "use-file-for-fake-audio-capture";
 
 // Enables support for inband text tracks in media content.
 const char kEnableInbandTextTracks[] = "enable-inband-text-tracks";
 
+// When running tests on a system without the required hardware or libraries,
+// this flag will cause the tests to fail. Otherwise, they silently succeed.
+const char kRequireAudioHardwareForTesting[] =
+    "require-audio-hardware-for-testing";
+
 }  // namespace switches