Add a mojo implementation of AudioOutputIPC.

content/public/common/content_features.cc

 // Copyright 2015 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 "build/build_config.h"
 #include "content/public/common/content_features.h"
 
 namespace features {
 
 // All features in alphabetical order.
@@ skipping 208 matching lines @@
 
 // Enables token binding
 // (https://www.ietf.org/id/draft-ietf-tokbind-protocol-04.txt).
 const base::Feature kTokenBinding{"token-binding",
                                   base::FEATURE_DISABLED_BY_DEFAULT};
 
 // Enables touchpad and wheel scroll latching.
 const base::Feature kTouchpadAndWheelScrollLatching{
     "TouchpadAndWheelScrollLatching", base::FEATURE_DISABLED_BY_DEFAULT};
 
+// Use MojoAudioOutputIPC and RenderFrameAudioOutputStreamFactory rather than
+// AudioMessageFilter and AudioRendererHost.
+const base::Feature kUseMojoAudioOutputStreamFactory{
+    "UseMojoAudioOutputStreamFactory", base::FEATURE_DISABLED_BY_DEFAULT};

[o1ka, 2017/04/20 10:35:59]

This is "enabling a feature behind a flag", so it needs to be mentioned in the
CL description.

I would do it in a separate CL though (see
https://codereview.chromium.org/2108673004 as an example of switching to a
feature later): it would be cheaper to revert. 

Do we want to have separate experiments for input and output? Since mirroring
connects outputs with inputs they are not totally independent. We'll end up with
4 experimental subsets instead of 2.

[Max Morin, 2017/05/05 13:10:58]

I removed the feature.
The hope is that this will be done before input. :)

+
 // Enables VR UI.
 const base::Feature kVrShell{"VrShell", base::FEATURE_DISABLED_BY_DEFAULT};
 
 // Enable WebAssembly.
 // http://webassembly.org/
 const base::Feature kWebAssembly{"WebAssembly",
                                  base::FEATURE_DISABLED_BY_DEFAULT};
 
 // If WebGL Image Chromium is allowed, this feature controls whether it is
 // enabled.
@@ skipping 71 matching lines @@
 #endif  // !defined(OS_ANDROID)
 
 #if defined(OS_WIN)
 // Emergency "off switch" for new Windows sandbox security mitigation,
 // sandbox::MITIGATION_EXTENSION_POINT_DISABLE.
 const base::Feature kWinSboxDisableExtensionPoints{
     "WinSboxDisableExtensionPoint", base::FEATURE_ENABLED_BY_DEFAULT};
 #endif
 
 }  // namespace features