Move the following files to content\public\plugin.

content/content_plugin.gypi

 # 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.
 
 {
   'dependencies': [
     '../skia/skia.gyp:skia',
     '../third_party/npapi/npapi.gyp:npapi',
     '../webkit/support/webkit_support.gyp:glue',
   ],
   'include_dirs': [
     '<(INTERMEDIATE_DIR)',
   ],
   'sources': [
     # All .cc, .h, .m, and .mm files under plugins except for tests and
     # mocks.
-    'plugin/content_plugin_client.h',
     'plugin/plugin_channel.cc',
     'plugin/plugin_channel.h',
     'plugin/plugin_interpose_util_mac.mm',
     'plugin/plugin_interpose_util_mac.h',
     'plugin/plugin_main.cc',
     'plugin/plugin_main_linux.cc',
     'plugin/plugin_main_mac.mm',
     'plugin/plugin_thread.cc',
     'plugin/plugin_thread.h',
     'plugin/webplugin_accelerated_surface_proxy_mac.cc',
     'plugin/webplugin_accelerated_surface_proxy_mac.h',
     'plugin/webplugin_delegate_stub.cc',
     'plugin/webplugin_delegate_stub.h',
     'plugin/webplugin_proxy.cc',
     'plugin/webplugin_proxy.h',
+    'public/plugin/content_plugin_client.h',
   ],
   # These are layered in conditionals in the event other platforms
   # end up using this module as well.
   'conditions': [
     ['OS=="win"', {
       'include_dirs': [
         '<(DEPTH)/third_party/wtl/include',
       ],
     }],
     ['toolkit_uses_gtk == 1', {
       'dependencies': [
         '../build/linux/system.gyp:gtk',
       ],
       'link_settings': {
         'libraries': [
           '-lXext',
         ],
       },
     }],
   ],
 }