Render the tab close button as a vector-based icon.

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

Index: chrome/browser/ui/views/tabs/media_indicator_button.h
diff --git a/chrome/browser/ui/views/tabs/media_indicator_button.h b/chrome/browser/ui/views/tabs/media_indicator_button.h
index e605cca9d28660feaa45294909b118c425204fe6..c5e7852cc8e1758edbe1600d003aaec1b213b42a 100644
--- a/chrome/browser/ui/views/tabs/media_indicator_button.h
+++ b/chrome/browser/ui/views/tabs/media_indicator_button.h
@@ -40,8 +40,8 @@ class MediaIndicatorButton : public views::ImageButton,
     return showing_media_state_;
   }
 
-  // Updates ImageButton images, starts fade animations, and
-  // activates/deactivates button functionality as appropriate.
+  // Calls ResetImages(), starts fade animations, and activates/deactivates
+  // button functionality as appropriate.
   void TransitionToMediaState(TabMediaState next_state);
 
   // Determines whether the MediaIndicatorButton will be clickable for toggling
@@ -50,6 +50,10 @@ class MediaIndicatorButton : public views::ImageButton,
   // calls this when the TabMediaState or the bounds have changed.
   void UpdateEnabledForMuteToggle();
 
+  // Called when the parent tab's button color changes.  Determines whether
+  // ResetImages() needs to be called.
+  void OnParentTabButtonColorChanged();
+
  protected:
   // views::View:
   const char* GetClassName() const override;
@@ -77,6 +81,10 @@ class MediaIndicatorButton : public views::ImageButton,
   // Returns the tab (parent view) of this MediaIndicatorButton.
   Tab* GetTab() const;
 
+  // Resets the images to display on the button to reflect |state| and the
+  // parent tab's button color.  Should be called when either of these changes.
+  void ResetImages(TabMediaState state);
+
   Tab* const parent_tab_;
 
   TabMediaState media_state_;