[Mac]Implement ViewID support.

chrome/browser/cocoa/tab_controller.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.
 
 #include "app/l10n_util_mac.h"
 #include "base/mac_util.h"
 #import "chrome/browser/browser_theme_provider.h"
 #import "chrome/browser/cocoa/menu_controller.h"
 #import "chrome/browser/cocoa/tab_controller.h"
 #import "chrome/browser/cocoa/tab_controller_target.h"
@@ skipping 296 matching lines @@
 
 // Called by the tabs to determine whether we are in rapid (tab) closure mode.
 - (BOOL)inRapidClosureMode {
   if ([[self target] respondsToSelector:@selector(inRapidClosureMode)]) {
     return [[self target] performSelector:@selector(inRapidClosureMode)] ?
         YES : NO;
   }
   return NO;
 }
 
+- (ViewID)viewID {
+  NSInteger total = 0;
+  NSInteger index = [[self target] indexForTabController:self inTotal:&total];
+  DCHECK(index >= 0 && index < total);
+
+  if (index >= 0 && index <= (VIEW_ID_TAB_9 - VIEW_ID_TAB_0))
+    return static_cast<ViewID>(index + VIEW_ID_TAB_0);
+  else if (index == total - 1)
+    return VIEW_ID_TAB_LAST;
+  return VIEW_ID_NONE;
+}
+
 @end