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 <string>
 #include <vector>
 
 #include "base/memory/scoped_ptr.h"
 #include "base/strings/string16.h"
+#include "content/public/browser/web_contents_user_data.h"
 
 class TabStripModel;
 
 namespace content {
 class WebContents;
 }  // namespace content
 
 namespace gfx {
 class Animation;
 class Image;
 }  // namespace gfx
 
 // Media state for a tab.  In reality, more than one of these may apply.  See
 // comments for GetTabMediaStateForContents() below.
 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 {
 
+// String to indicate reason for muted state change (user, capture, extension
+// id, or empty string)
+const char kMutedToggleCauseUser[] = "user";
+const char kMutedToggleCauseCapture[] = "auto-forced for capture";
+
 // 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);
+
+// Get cause of mute (extensionid, kMutedToggleCause constant, or empty string)
+std::string& GetTabAudioMutedCause(content::WebContents* contents);

[miu, 2015/01/22 00:55:23]

Please make the return type const std::string& to avoid external mutation of the
string.

 
 // 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_