Make tab audible and muted states and cause available for an extension API

chrome/browser/ui/tabs/tab_utils.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 CHROME_BROWSER_UI_TABS_TAB_UTILS_H_
 #define CHROME_BROWSER_UI_TABS_TAB_UTILS_H_
 
 #include <vector>
 
 #include "base/memory/scoped_ptr.h"
@@ skipping 15 matching lines @@
 enum TabMediaState {
   TAB_MEDIA_STATE_NONE,
   TAB_MEDIA_STATE_RECORDING,  // Audio/Video being recorded, consumed by tab.
   TAB_MEDIA_STATE_CAPTURING,  // Tab contents being captured.
   TAB_MEDIA_STATE_AUDIO_PLAYING,  // Audible audio is playing from the tab.
   TAB_MEDIA_STATE_AUDIO_MUTING,  // Tab audio is being muted.
 };
 
 namespace chrome {
 
+const char kUserMuteToggleCause[] = "user";

[miu, 2014/12/09 01:56:24]

You should only declare the constant here:

  const char kUserMuteToggleCause[];

And define it in the tab_utils.cc file:

  const char kUserMuteToggleCause[] = "user";

That'll resolve the concern you had about building the string into every file
that includes tab_utils.h.  ;-)

[sky, 2014/12/09 16:37:45]

Is there a reason this is a string and not an enum? If you need a string at a
later date you can always map the enum to a string internally when needed.

+
 // Logic to determine which components (i.e., close button, favicon, and media
 // indicator) of a tab should be shown, given current state.  |capacity|
 // specifies how many components can be shown, given available tab width.
 //
 // Precedence rules for deciding what to show when capacity is insufficient to
 // show everything:
 //
 //   Active tab: Always show the close button, then the media indicator, then
 //               the favicon.
 //   Inactive tab: Media indicator, then the favicon, then the close button.
@@ skipping 46 matching lines @@
 
 // Returns true if the experimental tab audio mute feature is enabled.
 bool IsTabAudioMutingFeatureEnabled();
 
 // Returns true if audio mute can be activated/deactivated for the given
 // |contents|.
 bool CanToggleAudioMute(content::WebContents* contents);
 
 // Indicates/Sets whether all audio output from |contents| is muted.
 bool IsTabAudioMuted(content::WebContents* contents);
-void SetTabAudioMuted(content::WebContents* contents, bool mute);
+void SetTabAudioMuted(content::WebContents* contents,
+                      bool muted,
+                      const std::string& cause);
 
 // Returns true if the tabs at the |indices| in |tab_strip| are all muted.
 bool AreAllTabsMuted(const TabStripModel& tab_strip,
                      const std::vector<int>& indices);
 
 }  // namespace chrome
 
 #endif  // CHROME_BROWSER_UI_TABS_TAB_UTILS_H_