[Mac] Update tab audio icon to Material Design and tweak close box color.

chrome/browser/ui/cocoa/tabs/alert_indicator_button_cocoa.h

Index: chrome/browser/ui/cocoa/tabs/alert_indicator_button_cocoa.h
diff --git a/chrome/browser/ui/cocoa/tabs/alert_indicator_button_cocoa.h b/chrome/browser/ui/cocoa/tabs/alert_indicator_button_cocoa.h
index c17583ed2b1a77431a9a60251a3ac6d65e3adb0e..94c556ff9887d0e647213cc79d56effca5db7f51 100644
--- a/chrome/browser/ui/cocoa/tabs/alert_indicator_button_cocoa.h
+++ b/chrome/browser/ui/cocoa/tabs/alert_indicator_button_cocoa.h
@@ -8,6 +8,7 @@
 #include <memory>
 
 #import "base/mac/scoped_nsobject.h"
+#import "chrome/browser/ui/cocoa/themed_window.h"
 #include "chrome/browser/ui/tabs/tab_utils.h"
 #import "ui/base/cocoa/hover_button.h"
 
@@ -27,7 +28,7 @@ class AnimationDelegate;
 //
 // Note: Send the |-setClickTarget:withAction:| message instead of the
 // |-setTarget:| and |-setAction:| messages to be notified of button clicks.
-@interface AlertIndicatorButton : HoverButton {
+@interface AlertIndicatorButton : HoverButton <ThemedWindowDrawing> {
  @private
   class FadeAnimationDelegate;
 
@@ -79,6 +80,10 @@ class AnimationDelegate;
 // clicked.  A weak reference on |target| is held.
 - (void)setClickTarget:(id)target withAction:(SEL)action;
 
+// ThemedWindowDrawing protocol support.
+- (void)windowDidChangeTheme;
+- (void)windowDidChangeActive;
+
 @end
 
 #endif  // CHROME_BROWSER_UI_COCOA_TABS_ALERT_INDICATOR_BUTTON_COCOA_H_