Clean up error handling logic for extension tab muting

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 2ca81514a81b2d0486e6534def812969cb610cd2..99cb42f1690d570b6f63154895ef1f58948a898d 100644
--- a/chrome/browser/ui/tabs/tab_utils.h
+++ b/chrome/browser/ui/tabs/tab_utils.h
@@ -7,7 +7,7 @@
 
 #include <string>
 #include <vector>
-
+#include "base/containers/hash_tables.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/strings/string16.h"
 #include "content/public/browser/web_contents_user_data.h"
@@ -33,6 +33,13 @@ enum TabMediaState {
   TAB_MEDIA_STATE_AUDIO_MUTING,  // Tab audio is being muted.
 };
 
+enum TabMutedResult {
+  TAB_MUTED_RESULT_SUCCESS,
+  TAB_MUTED_RESULT_FAIL_NOT_ENABLED,
+  TAB_MUTED_RESULT_FAIL_TABCAPTURE,
+  TAB_MUTED_RESULT_FAIL_RATE_LIMITED,
+};
+
 namespace chrome {
 
 // String to indicate reason for muted state change (user, capture, extension
@@ -40,6 +47,11 @@ namespace chrome {
 extern const char kMutedToggleCauseUser[];
 extern const char kMutedToggleCauseCapture[];
 
+// Constants for rate limiting mute updating by extensions
+extern const int kMuteTokenBucketCostSeconds = 15;

[miu, 2015/07/16 00:28:26]

style nit: Assignment of the constant needs to be in the .cc file (see my
example from last round of review comments).

Alternatively, you could define these two constants as:

enum {
  kMuteTokenBucketCostSeconds = 15,
  kMuteTokenBucketCapacitySeconds = 45
};

+extern const int kMuteTokenBucketCapacitySeconds =
+    3 * kMuteTokenBucketCostSeconds;
+
 // 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.
@@ -104,18 +116,24 @@ bool IsTabAudioMutingFeatureEnabled();
 // |contents|.
 bool CanToggleAudioMute(content::WebContents* contents);
 
+// Returns true if extension-driven muting is rate limited for a tab
+bool IsTabAudioMutedRateLimited(content::WebContents* contents);
+
 // Indicates whether all audio output from |contents| is muted.
 bool IsTabAudioMuted(content::WebContents* contents);
 
 // Sets whether all audio output from |contents| is muted.
 // Cause is extensionid, kMutedToggleCause constant, or empty string
-void SetTabAudioMuted(content::WebContents* contents,
-                      bool mute,
-                      const std::string& cause);
+TabMutedResult SetTabAudioMuted(content::WebContents* contents,
+                                bool mute,
+                                const std::string& cause);
 
 // Get cause of mute (extensionid, kMutedToggleCause constant, or empty string)
 const std::string& GetTabAudioMutedCause(content::WebContents* contents);
 
+// Update token buckets for rate limiting muting using elapsed time
+void updateTokenBuckets(content::WebContents* contents);

[miu, 2015/07/16 00:28:26]

Also, don't declare this function in the header file.  It should be private
within tab_utils.cc.

[miu, 2015/07/16 00:28:26]

style: The "u" in updateTokenBuckets needs to be captialized.

+
 // 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);