Add missing include guards in Cocoa code.

chrome/browser/ui/cocoa/bookmarks/bookmark_bar_folder_hover_state.h

 // Copyright (c) 2011 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_UI_COCOA_BOOKMARKS_BOOKMARK_BAR_FOLDER_HOVER_STATE_H_
+#define CHROME_BROWSER_UI_COCOA_BOOKMARKS_BOOKMARK_BAR_FOLDER_HOVER_STATE_H_
+
 #import <Cocoa/Cocoa.h>
 
 #include "base/mac/scoped_nsobject.h"
 #import "chrome/browser/ui/cocoa/bookmarks/bookmark_button.h"
 
 // Hover state machine.  Encapsulates the hover state for
 // BookmarkBarFolderController.
 // A strict call order is implied with these calls.  It is ONLY valid to make
 // the following state transitions:
 // From:            To:               Via:
@@ skipping 54 matching lines @@
 - (void)scheduleOpenBookmarkFolderOnHoverButton:(BookmarkButton*)hoverButton;
 - (void)cancelPendingOpenBookmarkFolderOnHoverButton;
 @end
 
 // Exposing these for unit testing purposes.  They are used only in tests.
 @interface BookmarkBarFolderHoverState(TestingAPI)
 // Accessors and setters for button and hover state.
 - (BookmarkButton*)hoverButton;
 - (HoverState)hoverState;
 @end
+
+#endif  // CHROME_BROWSER_UI_COCOA_BOOKMARKS_BOOKMARK_BAR_FOLDER_HOVER_STATE_H_