Merge 661693003 to M39: Avoid reporting 0 as input level when AudioProcessing zero out the audio da…

content/renderer/media/media_stream_audio_level_calculator.h

 // Copyright 2014 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_MEDIA_STREAM_AUDIO_LEVEL_CALCULATOR_H_
 #define CONTENT_RENDERER_MEDIA_MEDIA_STREAM_AUDIO_LEVEL_CALCULATOR_H_
 
 #include "base/threading/thread_checker.h"
 
 namespace content {
 
 // This class is used by the WebRtcLocalAudioTrack to calculate the  level of
 // the audio signal. And the audio level will be eventually used by the volume
 // animation UI.
 // The algorithm used by this class is the same as how it is done in
 // third_party/webrtc/voice_engine/level_indicator.cc.
 class MediaStreamAudioLevelCalculator {
  public:
   MediaStreamAudioLevelCalculator();
   ~MediaStreamAudioLevelCalculator();
 
   // Calculates the signal level of the audio data.
   // Returns the absolute value of the amplitude of the signal.
+  // |force_report_nonzero_energy| is a flag forcing the calculator to
+  // report nonzero energy even if the energy of the processed audio is zero.
+  // Since |audio_data| is post processed data, and the audio processing might
+  // zero all the audio data, when the caller detects the pre processed data
+  // contain energy, it could pass |force_report_nonzero_energy| as true to
+  // force calculator to report 1 as energy when |audio_data| is all zero.
   int Calculate(const int16* audio_data, int number_of_channels,
-                int number_of_frames);
+                int number_of_frames, bool force_report_nonzero_energy);
 
  private:
   // Used to DCHECK that the constructor and Calculate() are always called on
   // the same audio thread. Note that the destructor will be called on a
   // different thread, which can be either the main render thread or a new
   // audio thread where WebRtcLocalAudioTrack::OnSetFormat() is called.
   base::ThreadChecker thread_checker_;
 
   int counter_;
   int max_amplitude_;
   int level_;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_MEDIA_MEDIA_STREAM_AUDIO_LEVEL_CALCULATOR_H_