[Mac]Implement ViewID support.

chrome/browser/cocoa/tab_controller.h

 // 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.
 
 #ifndef CHROME_BROWSER_COCOA_TAB_CONTROLLER_H_
 #define CHROME_BROWSER_COCOA_TAB_CONTROLLER_H_
 
 #import <Cocoa/Cocoa.h>
 #import "chrome/browser/cocoa/hover_close_button.h"
 #include "chrome/browser/tab_menu_model.h"
+#include "chrome/browser/view_ids.h"
 
 // The loading/waiting state of the tab.
 enum TabLoadingState {
   kTabDone,
   kTabLoading,
   kTabWaiting,
   kTabCrashed,
 };
 
 @class MenuController;
@@ skipping 74 matching lines @@
 // Ideally, tabs would know about their own animation and wouldn't need this.
 - (BOOL)inRapidClosureMode;
 
 // Updates the visibility of certain subviews, such as the icon and close
 // button, based on criteria such as the tab's selected state and its current
 // width.
 - (void)updateVisibility;
 
 // Update the title color to match the tabs current state.
 - (void)updateTitleColor;
+
+// Returns the ViewID of the tab.
+- (ViewID)viewID;
+
 @end
 
 @interface TabController(TestingAPI)
 - (NSString*)toolTip;
 - (int)iconCapacity;
 - (BOOL)shouldShowIcon;
 - (BOOL)shouldShowCloseButton;
 @end  // TabController(TestingAPI)
 
 #endif  // CHROME_BROWSER_COCOA_TAB_CONTROLLER_H_