WebContentsAudioMuter: Mute all audio output from a WebContentsImpl.

content/public/browser/web_contents.h

 // Copyright (c) 2012 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_PUBLIC_BROWSER_WEB_CONTENTS_H_
 #define CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_H_
 
 #include <set>
 
 #include "base/basictypes.h"
@@ skipping 288 matching lines @@
   // Indicates whether the WebContents is being captured (e.g., for screenshots
   // or mirroring).  Increment calls must be balanced with an equivalent number
   // of decrement calls.  |capture_size| specifies the capturer's video
   // resolution, but can be empty to mean "unspecified."  The first screen
   // capturer that provides a non-empty |capture_size| will override the value
   // returned by GetPreferredSize() until all captures have ended.
   virtual void IncrementCapturerCount(const gfx::Size& capture_size) = 0;
   virtual void DecrementCapturerCount() = 0;
   virtual int GetCapturerCount() const = 0;
 
+  // Indicates/Sets whether all audio output from this WebContents is muted.
+  virtual bool IsAudioMuted() const = 0;

[DaleCurtis, 2014/09/22 17:45:45]

I don't see this one used anywhere?

[miu, 2014/09/22 19:44:58]

It will be used by the UI code.  See https://codereview.chromium.org/591963002/.

+  virtual void SetAudioMuted(bool mute) = 0;
+
   // Indicates whether this tab should be considered crashed. The setter will
   // also notify the delegate when the flag is changed.
   virtual bool IsCrashed() const  = 0;
   virtual void SetIsCrashed(base::TerminationStatus status, int error_code) = 0;
 
   virtual base::TerminationStatus GetCrashedStatus() const = 0;
 
   // Whether the tab is in the process of being destroyed.
   virtual bool IsBeingDestroyed() const = 0;
 
@@ skipping 281 matching lines @@
 
  private:
   // This interface should only be implemented inside content.
   friend class WebContentsImpl;
   WebContents() {}
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_H_