Fix tab focus/blur events on tab switch on the Mac

chrome/browser/cocoa/tab_contents_controller.h

 // Copyright (c) 2009 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_CONTENTS_CONTROLLER_H_
 #define CHROME_BROWSER_COCOA_TAB_CONTENTS_CONTROLLER_H_
 
 #include <Cocoa/Cocoa.h>
 
 class TabContents;
@@ skipping 13 matching lines @@
   TabContents* contents_;  // weak
 
   IBOutlet NSBox* contentsBox_;
 }
 
 // Create the contents of a tab represented by |contents| and loaded from the
 // nib given by |name|.
 - (id)initWithNibName:(NSString*)name
              contents:(TabContents*)contents;
 
+// Called when the tab contents is the currently selected tab and is about to be
+// removed from the view hierarchy.
+- (void)willBecomeUnselectedTab;
+
 // Called when the tab contents is about to be put into the view hierarchy as
 // the selected tab. Handles things such as ensuring the toolbar is correctly
 // enabled.
 - (void)willBecomeSelectedTab;
 
 // Call when the tab view is properly sized and the render widget host view
 // should be put into the view hierarchy.
 - (void)ensureContentsVisible;
 
 // Called when the tab contents is updated in some non-descript way (the
 // notification from the model isn't specific). |updatedContents| could reflect
 // an entirely new tab contents object.
 - (void)tabDidChange:(TabContents*)updatedContents;
 
 @end
 
 #endif  // CHROME_BROWSER_COCOA_TAB_CONTENTS_CONTROLLER_H_