mac: Make the avatar button layer backed.

chrome/browser/ui/cocoa/browser_window_controller_private.h

Index: chrome/browser/ui/cocoa/browser_window_controller_private.h
diff --git a/chrome/browser/ui/cocoa/browser_window_controller_private.h b/chrome/browser/ui/cocoa/browser_window_controller_private.h
index c4c57a17366b31c92dd350733c1325aa17e66737..cf0711310d67751539e47e55fa33973f49f4f1bb 100644
--- a/chrome/browser/ui/cocoa/browser_window_controller_private.h
+++ b/chrome/browser/ui/cocoa/browser_window_controller_private.h
@@ -137,6 +137,9 @@
 // The opacity for the toolbar divider; 0 means that it shouldn't be shown.
 - (CGFloat)toolbarDividerOpacity;
 
+// Removes the view from its superview, then adds it back in the same place.
+- (void)reAddViewToSuperview:(NSView*)view;

[Avi (use Gerrit), 2014/09/11 18:26:49]

First, this comment is not helpful; it merely restates the name of the method.

But much more importantly, name this function after _what it does_, not how it
does it. Why would someone want to call this method? What does it accomplish?
The fact that it does so by removing and re-adding the view is an implementation
detail.

I'm seriously staring at this code and it makes no sense.

[erikchen, 2014/09/12 00:32:51]

I updated the comment and the name of the method as per your suggestions.

+
 // Ensures the z-order of subviews is correct.
 - (void)updateSubviewZOrder:(BOOL)inPresentationMode;