Move extension_icon_set.{h,cc} to //extensions

extensions/extensions.gyp

 # Copyright 2013 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.
 
 {
   'variables': {
     'chromium_code': 1,
   },
   'targets': [
     {
@@ skipping 46 matching lines @@
         'common/event_filter.h',
         'common/event_filtering_info.cc',
         'common/event_filtering_info.h',
         'common/event_matcher.cc',
         'common/event_matcher.h',
         'common/extension.cc',
         'common/extension.h',
         'common/extension_api.cc',
         'common/extension_api.h',
         'common/extension_api_stub.cc',
+        'common/extension_icon_set.cc',
+        'common/extension_icon_set.h',
         'common/extension_message_generator.cc',
         'common/extension_message_generator.h',
         'common/extension_messages.cc',
         'common/extension_messages.h',
         'common/extension_paths.cc',
         'common/extension_paths.h',
         'common/extension_resource.cc',
         'common/extension_resource.h',
         'common/extension_set.cc',
         'common/extension_set.h',
@@ skipping 387 matching lines @@
         'common/one_shot_event_unittest.cc',
         'common/permissions/api_permission_set_unittest.cc',
         'common/permissions/manifest_permission_set_unittest.cc',
         'common/url_pattern_set_unittest.cc',
         'common/url_pattern_unittest.cc',
         'common/user_script_unittest.cc',
       ],
     },
   ]
 }