Added an "enable-audio-processor" flag and WebRtcAudioProcessor class

content/renderer/media/webrtc_audio_processor_options.h

+// 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.
+
+#ifndef CONTENT_RENDERER_MEDIA_WEBRTC_AUDIO_PROCESSOR_OPTIONS_H_
+#define CONTENT_RENDERER_MEDIA_WEBRTC_AUDIO_PROCESSOR_OPTIONS_H_
+
+#include <string>
+
+namespace webrtc {
+
+class AudioFrame;
+class AudioProcessing;
+class MediaConstraintsInterface;
+
+}
+
+namespace content {
+
+using webrtc::AudioProcessing;
+using webrtc::MediaConstraintsInterface;
+
+bool GetPropertyFromConstraints(

[Jói, 2013/11/08 13:36:40]

All of these methods need comments.

[no longer working on chromium, 2013/11/08 15:39:30]

Done.

+    const MediaConstraintsInterface* constraints,
+    const std::string& key);
+
+void EnableEchoCancellation(AudioProcessing* audio_processing);

[Jói, 2013/11/08 13:36:40]

I guess I don't understand the motivation here well enough. Why do these act on
AudioProcessing instead of WebRtcAudioProcessor? Also, why aren't they just
members of WebRtcAudioProcessing?

[no longer working on chromium, 2013/11/08 15:39:30]

AudioProcessing is the webrtc components which does all the processing on the
signal, like aec, ns, agc, ..etc.
WebRtcAudioProcessor is the class owns and use AudioProcessing.

The reason why I extract these methods out to a separate files is that the list
of the methods will grow substantially when we support more features. The list
in this CL is just part of it.
And the plan is to gradually support all the features behind a flag, then turn
on the flag by default.

+
+void EnableNoiseSuppression(AudioProcessing* audio_processing);
+
+void EnableHighPassFilter(AudioProcessing* audio_processing);
+
+void EnableTypingDetection(AudioProcessing* audio_processing);
+
+void EnableExperimentalEchoCancellation(AudioProcessing* audio_processing);
+
+void StartAecDump(AudioProcessing* audio_processin);
+
+void StopAecDump(AudioProcessing* audio_processin);
+
+}  // namespace content
+
+#endif  // CONTENT_RENDERER_MEDIA_WEBRTC_AUDIO_PROCESSOR_OPTIONS_H_