Add support for audio input mute detection on all platforms

content/browser/media/capture/web_contents_audio_input_stream.h

 // Copyright (c) 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.
 //
 // An AudioInputStream which provides a loop-back of all audio output generated
 // by the entire RenderFrame tree associated with a WebContents instance.  The
 // single stream of data is produced by format-converting and mixing all audio
 // output streams.  As the RenderFrameHost tree mutates (e.g., due to page
 // navigations, or crashes/reloads), the stream will continue without
 // interruption.  In other words, WebContentsAudioInputStream provides tab-level
@@ skipping 28 matching lines @@
   // media::AudioInputStream implementation
   virtual bool Open() override;
   virtual void Start(AudioInputCallback* callback) override;
   virtual void Stop() override;
   virtual void Close() override;
   virtual double GetMaxVolume() override;
   virtual void SetVolume(double volume) override;
   virtual double GetVolume() override;
   virtual void SetAutomaticGainControl(bool enabled) override;
   virtual bool GetAutomaticGainControl() override;
+  virtual bool IsMuted() override;
 
   // Create a new audio mirroring session, or return NULL on error.  |device_id|
   // should be in the format accepted by
   // WebContentsCaptureUtil::ExtractTabCaptureTarget().  The caller must
   // guarantee Close() is called on the returned object so that it may
   // self-destruct.
   // |worker_task_runner| is the task runner on which AudioInputCallback methods
   // are called and may or may not be the single thread that invokes the
   // AudioInputStream methods.
   static WebContentsAudioInputStream* Create(
@@ skipping 21 matching lines @@
   virtual ~WebContentsAudioInputStream();
 
   scoped_refptr<Impl> impl_;
 
   DISALLOW_COPY_AND_ASSIGN(WebContentsAudioInputStream);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_MEDIA_CAPTURE_WEB_CONTENTS_AUDIO_INPUT_STREAM_H_