[Mac]Implement ViewID support.

chrome/browser/cocoa/toolbar_view.mm

Index: chrome/browser/cocoa/toolbar_view.mm
diff --git a/chrome/browser/cocoa/toolbar_view.mm b/chrome/browser/cocoa/toolbar_view.mm
index 75a893f92dfed1727c7830141629cf435e5c1791..ee336042db5fcce5d145915c8db63bcccdc76e93 100644
--- a/chrome/browser/cocoa/toolbar_view.mm
+++ b/chrome/browser/cocoa/toolbar_view.mm
@@ -1,10 +1,11 @@
-  // Copyright (c) 2009 The Chromium Authors. All rights reserved.
+  // Copyright (c) 2010 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/cocoa/toolbar_view.h"
 
 #import "chrome/browser/cocoa/themed_window.h"
+#import "chrome/browser/cocoa/view_id_util.h"
 
 @implementation ToolbarView
 
@@ -39,4 +40,9 @@
   return [super accessibilityAttributeValue:attribute];
 }
 
+// Tag is used solely for ViewID. Override to prevent changing of it.
+- (NSInteger)tag {
+  return view_id_util::ViewIDToTag(VIEW_ID_TOOLBAR);
+}
+
 @end