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

chrome/browser/ui/tabs/tab_utils.h

Index: chrome/browser/ui/tabs/tab_utils.h
diff --git a/chrome/browser/ui/tabs/tab_utils.h b/chrome/browser/ui/tabs/tab_utils.h
index 4480a41609f149cbc48f01466975e4358718eaa5..b0cd17294db863a42a669e27c9813283e6899fb6 100644
--- a/chrome/browser/ui/tabs/tab_utils.h
+++ b/chrome/browser/ui/tabs/tab_utils.h
@@ -33,6 +33,10 @@ enum TabMediaState {
 
 namespace chrome {
 
+// String to indicate that muted state change was caused by user (instead of
+// initial, capture, an extension id).
+const char kMutedToggleCauseUser[] = "user";
+
 // 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.
@@ -99,7 +103,9 @@ 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,