Remove media_galleries_handlers - not used.

chrome/chrome_common.gypi

 # Copyright (c) 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': {
     'chrome_common_sources': [
       '../apps/app_shim/app_shim_launch.h',
       '../apps/app_shim/app_shim_messages.h',
       'common/all_messages.h',
@@ skipping 66 matching lines @@
       'common/extensions/api/file_browser_handlers/file_browser_handler.cc',
       'common/extensions/api/file_browser_handlers/file_browser_handler.h',
       'common/extensions/api/i18n/default_locale_handler.cc',
       'common/extensions/api/i18n/default_locale_handler.h',
       'common/extensions/api/identity/oauth2_manifest_handler.cc',
       'common/extensions/api/identity/oauth2_manifest_handler.h',
       'common/extensions/api/input_ime/input_components_handler.cc',
       'common/extensions/api/input_ime/input_components_handler.h',
       'common/extensions/api/managed_mode_private/managed_mode_handler.cc',
       'common/extensions/api/managed_mode_private/managed_mode_handler.h',
-      'common/extensions/api/media_galleries_private/media_galleries_handler.h',
-      'common/extensions/api/media_galleries_private/media_galleries_handler.cc',
       'common/extensions/api/notifications/notification_style.cc',
       'common/extensions/api/notifications/notification_style.h',
       'common/extensions/api/omnibox/omnibox_handler.cc',
       'common/extensions/api/omnibox/omnibox_handler.h',
       'common/extensions/api/plugins/plugins_handler.cc',
       'common/extensions/api/plugins/plugins_handler.h',
       'common/extensions/api/speech/tts_engine_manifest_handler.cc',
       'common/extensions/api/speech/tts_engine_manifest_handler.h',
       'common/extensions/api/spellcheck/spellcheck_handler.cc',
       'common/extensions/api/spellcheck/spellcheck_handler.h',
@@ skipping 596 matching lines @@
         'common/metrics/proto/chrome_experiments.proto',
       ],
       'variables': {
         'proto_in_dir': 'common/metrics/proto',
         'proto_out_dir': 'chrome/common/metrics/proto',
       },
       'includes': [ '../build/protoc.gypi' ],
     },
   ],
 }