Tab audio mute control (views UI), behind a switch (off by default).

chrome/browser/ui/views/tabs/tab.h

Index: chrome/browser/ui/views/tabs/tab.h
diff --git a/chrome/browser/ui/views/tabs/tab.h b/chrome/browser/ui/views/tabs/tab.h
index ff9d9b1fd8e56117218c15e7588c05e044adb778..80ff350e69b8c255cbbaba7b1fd59692cd4d4bb9 100644
--- a/chrome/browser/ui/views/tabs/tab.h
+++ b/chrome/browser/ui/views/tabs/tab.h
@@ -147,6 +147,7 @@ class Tab : public gfx::AnimationDelegate,
 
   // The animation object used to swap the favicon with the sad tab icon.
   class FaviconCrashAnimation;
+  class MediaIndicatorButton;
   class TabCloseButton;
 
   // Contains a cached image and the values used to generate it.
@@ -225,9 +226,8 @@ class Tab : public gfx::AnimationDelegate,
                                                  int tab_id);
   void PaintActiveTabBackground(gfx::Canvas* canvas);
 
-  // Paints the favicon and media indicator icon, mirrored for RTL if needed.
+  // Paints the favicon, mirrored for RTL if needed.
   void PaintIcon(gfx::Canvas* canvas);
-  void PaintMediaIndicator(gfx::Canvas* canvas);
 
   // Invoked if data_.network_state changes, or the network_state is not none.
   void AdvanceLoadingAnimation(TabRendererData::NetworkState old_state,
@@ -264,10 +264,6 @@ class Tab : public gfx::AnimationDelegate,
   // Returns true if the crash animation is currently running.
   bool IsPerformingCrashAnimation() const;
 
-  // Starts the media indicator fade-in/out animation. There's no stop method
-  // because this is not a continuous animation.
-  void StartMediaIndicatorAnimation();
-
   // Schedules repaint task for icon.
   void ScheduleIconPaint();
 
@@ -279,6 +275,9 @@ class Tab : public gfx::AnimationDelegate,
                           int* tab_id,
                           int* frame_id) const;
 
+  // Returns |media_indicator_button_|, creating it on-demand.
+  MediaIndicatorButton* LazyGetMediaIndicatorButton();

[sky, 2014/09/23 22:58:18]

Nuke the 'Lazy'. That is, make it GetMediaIndicatorButton().

[miu, 2014/09/24 22:34:16]

Done.

+
   // Performs a one-time initialization of static resources such as tab images.
   static void InitTabResources();
 
@@ -335,14 +334,10 @@ class Tab : public gfx::AnimationDelegate,
   // Crash icon animation (in place of favicon).
   scoped_ptr<gfx::LinearAnimation> crash_icon_animation_;
 
-  // Media indicator fade-in/out animation (i.e., only on show/hide, not a
-  // continuous animation).
-  scoped_ptr<gfx::Animation> media_indicator_animation_;
-  TabMediaState animating_media_state_;
-
   scoped_refptr<gfx::AnimationContainer> animation_container_;
 
   views::ImageButton* close_button_;
+  MediaIndicatorButton* media_indicator_button_;  // NULL until first use.
   views::Label* title_;
 
   bool tab_activated_with_last_tap_down_;
@@ -351,7 +346,6 @@ class Tab : public gfx::AnimationDelegate,
 
   // The bounds of various sections of the display.
   gfx::Rect favicon_bounds_;
-  gfx::Rect media_indicator_bounds_;
 
   // The offset used to paint the inactive background image.
   gfx::Point background_offset_;