Put browser side mixing back behind a flag.

BUG=140247
TEST=Tried --enable-audio-mixer flag and observed regression.

Review URL: https://chromiumcodereview.appspot.com/10834159

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@149906 0039d316-1c4b-4281-b951-d872f2087c98

media/audio/audio_manager_base.cc

@@ -142,15 +142,13 @@ AudioOutputStream* AudioManagerBase::MakeAudioOutputStreamProxy(
   if (!dispatcher) {
     base::TimeDelta close_delay =
         base::TimeDelta::FromSeconds(kStreamCloseDelaySeconds);
-// TODO(dalecurtis): Temporarily disable the mixer for non-Windows/Mac platforms
-// until a fix for http://crbug.com/138098 can be found.
-#if defined(OS_WIN) || defined(OS_MACOSX)
     const CommandLine* cmd_line = CommandLine::ForCurrentProcess();
-    if (!cmd_line->HasSwitch(switches::kDisableAudioMixer)) {
+    // TODO(dalecurtis): Browser side mixing has a couple issues that must be
+    // fixed before it can be turned on by default: http://crbug.com/138098 and
+    // http://crbug.com/140247
+    if (cmd_line->HasSwitch(switches::kEnableAudioMixer)) {
       dispatcher = new AudioOutputMixer(this, params, close_delay);
-    } else
-#endif
-    {
+    } else {
       dispatcher = new AudioOutputDispatcherImpl(this, params, close_delay);
     }
   }

media/base/media_switches.cc

@@ -35,7 +35,7 @@ const char kEnableExclusiveAudio[] = "enable-exclusive-audio";
 // Set number of threads to use for video decoding.
 const char kVideoThreads[] = "video-threads";
 
-// Disables browser-side audio mixer.
-const char kDisableAudioMixer[] = "disable-audio-mixer";
+// Enable browser-side audio mixer.
+const char kEnableAudioMixer[] = "enable-audio-mixer";
 
 }  // namespace switches

media/base/media_switches.h

@@ -31,7 +31,7 @@ MEDIA_EXPORT extern const char kEnableExclusiveAudio[];
 
 MEDIA_EXPORT extern const char kVideoThreads[];
 
-MEDIA_EXPORT extern const char kDisableAudioMixer[];
+MEDIA_EXPORT extern const char kEnableAudioMixer[];
 
 }  // namespace switches