CoreAnimation: Fix text anti-aliasing in download shelf

chrome/browser/ui/cocoa/download/download_item_button.mm

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import "chrome/browser/ui/cocoa/download/download_item_button.h"
 
 #include "base/logging.h"
 #include "base/strings/sys_string_conversions.h"
 #import "chrome/browser/ui/cocoa/download/download_item_cell.h"
 #import "chrome/browser/ui/cocoa/download/download_item_controller.h"
 #import "chrome/browser/ui/cocoa/download/download_shelf_context_menu_controller.h"
+#import "chrome/browser/ui/cocoa/nsview_additions.h"
+#import "chrome/browser/ui/cocoa/view_id_util.h"
 
 @implementation DownloadItemButton
 
 @synthesize download = downloadPath_;
 @synthesize controller = controller_;
 
 // Overridden from DraggableButton.
 - (void)beginDrag:(NSEvent*)event {
   if (!downloadPath_.empty()) {
     NSString* filename = base::SysUTF8ToNSString(downloadPath_.value());
@@ skipping 31 matching lines @@
 }
 
 - (void)menuDidClose:(NSMenu*)menu {
   [[self cell] setHighlighted:NO];
 }
 
 - (BOOL)shouldDelayWindowOrderingForEvent:(NSEvent*)event {
   return YES;
 }
 
+- (BOOL)isOpaque {
+  // Make this control opaque so that sub-pixel anti-aliasing works when
+  // CoreAnimation is enabled.
+  return YES;
+}
+
+- (void)drawRect:(NSRect)rect {
+  NSView* downloadShelfView = [self ancestorWithViewID:VIEW_ID_DOWNLOAD_SHELF];
+  [self cr_drawUsingAncestor:downloadShelfView inRect:rect];
+  [super drawRect:rect];
+}
+
 @end