Add missing include guards in Cocoa code.

chrome/browser/ui/cocoa/location_bar/autocomplete_text_field_cell.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_UI_COCOA_LOCATION_BAR_AUTOCOMPLETE_TEXT_FIELD_CELL_H_
+#define CHROME_BROWSER_UI_COCOA_LOCATION_BAR_AUTOCOMPLETE_TEXT_FIELD_CELL_H_
+
 #include <vector>
 
 #import <Cocoa/Cocoa.h>
 
 #include "base/mac/scoped_nsobject.h"
 #import "chrome/browser/ui/cocoa/styled_text_field_cell.h"
 
 @class AutocompleteTextField;
 class LocationBarDecoration;
 
@@ skipping 123 matching lines @@
                   ofView:(AutocompleteTextField*)controlView;
 @end
 
 // Methods which are either only for testing, or only public for testing.
 @interface AutocompleteTextFieldCell (TestingAPI)
 
 // Returns |mouseTrackingDecorations_|.
 - (const std::vector<LocationBarDecoration*>&)mouseTrackingDecorations;
 
 @end
+
+#endif  // CHROME_BROWSER_UI_COCOA_LOCATION_BAR_AUTOCOMPLETE_TEXT_FIELD_CELL_H_