[Mac]Implement ViewID support.

chrome/browser/cocoa/tab_strip_view.mm

 // 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/tab_strip_view.h"
 
 #include "base/mac_util.h"
 #import "chrome/browser/cocoa/browser_window_controller.h"
 #import "chrome/browser/cocoa/tab_strip_controller.h"
+#import "chrome/browser/cocoa/view_id_util.h"
 #include "base/logging.h"
 
 @implementation TabStripView
 
 @synthesize newTabButton = newTabButton_;
 @synthesize dropArrowShown = dropArrowShown_;
 @synthesize dropArrowPosition = dropArrowPosition_;
 
 - (id)initWithFrame:(NSRect)frame {
   self = [super initWithFrame:frame];
@@ skipping 164 matching lines @@
   return NO;
 }
 
 - (id)accessibilityAttributeValue:(NSString*)attribute {
   if ([attribute isEqual:NSAccessibilityRoleAttribute])
     return NSAccessibilityGroupRole;
 
   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_TAB_STRIP);
+}
+
 @end