Refactor to move chrome_page_zoom functions to components/ui/zoom.

components/ui_zoom.gypi

 # Copyright 2014 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': 'ui_zoom',
       'type': 'static_library',
       'include_dirs': [
         '..',
       ],
       'dependencies': [
         '../base/base.gyp:base',
         '../content/content.gyp:content_browser',
         '../content/content.gyp:content_common',
         '../ipc/ipc.gyp:ipc',
         '../net/net.gyp:net',
         '../url/url.gyp:url_lib',
       ],
       'sources': [
+        'ui/zoom/page_zoom.cc',
+        'ui/zoom/page_zoom.h',
+        'ui/zoom/page_zoom_constants.cc',
+        'ui/zoom/page_zoom_constants.h',
         'ui/zoom/zoom_controller.cc',
         'ui/zoom/zoom_controller.h',
         'ui/zoom/zoom_event_manager.cc',
         'ui/zoom/zoom_event_manager.h',
         'ui/zoom/zoom_observer.h'
       ],
     }
   ],
 }