Refactor browser window zoom handling and enable zoom icon on all platforms.

chrome/chrome_browser.gypi

 # Copyright (c) 2012 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.
 
 {
   'targets': [
     {
       'target_name': 'browser',
       'type': 'static_library',
@@ skipping 2776 matching lines @@
         'browser/ui/cocoa/location_bar/location_icon_decoration.h',
         'browser/ui/cocoa/location_bar/location_icon_decoration.mm',
         'browser/ui/cocoa/location_bar/page_action_decoration.h',
         'browser/ui/cocoa/location_bar/page_action_decoration.mm',
         'browser/ui/cocoa/location_bar/plus_decoration.h',
         'browser/ui/cocoa/location_bar/plus_decoration.mm',
         'browser/ui/cocoa/location_bar/selected_keyword_decoration.h',
         'browser/ui/cocoa/location_bar/selected_keyword_decoration.mm',
         'browser/ui/cocoa/location_bar/star_decoration.h',
         'browser/ui/cocoa/location_bar/star_decoration.mm',
+        'browser/ui/cocoa/location_bar/zoom_decoration.h',
+        'browser/ui/cocoa/location_bar/zoom_decoration.mm',
         'browser/ui/cocoa/login_prompt_cocoa.h',
         'browser/ui/cocoa/login_prompt_cocoa.mm',
         'browser/ui/cocoa/main_menu_item.h',
         'browser/ui/cocoa/menu_button.h',
         'browser/ui/cocoa/menu_button.mm',
         'browser/ui/cocoa/menu_controller.h',
         'browser/ui/cocoa/menu_controller.mm',
         'browser/ui/cocoa/multi_key_equivalent_button.h',
         'browser/ui/cocoa/multi_key_equivalent_button.mm',
         'browser/ui/cocoa/new_tab_button.h',
@@ skipping 2659 matching lines @@
           'variables': {
             'jni_gen_dir': 'chrome',
           },
           'includes': [ '../build/jni_generator.gypi' ],
         },
       ],
      },
     ],
   ],
 }