Delete chrome_plugin_messages.h which is no longer used

chrome/chrome_common.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': 'common',
       'type': 'static_library',
       'variables': {
@@ skipping 59 matching lines @@
         'common/badge_util.cc',
         'common/badge_util.h',
         'common/bzip2_error_handler.cc',
         'common/child_process_logging.h',
         'common/child_process_logging_mac.mm',
         'common/child_process_logging_posix.cc',
         'common/child_process_logging_win.cc',
         'common/chrome_content_client.cc',
         'common/chrome_content_client.h',
         'common/chrome_notification_types.h',
-        'common/chrome_plugin_messages.h',
         'common/chrome_result_codes.h',
         'common/chrome_sandbox_type_mac.h',
         'common/chrome_utility_messages.h',
         'common/chrome_version_info.cc',
         'common/chrome_version_info_chromeos.cc',
         'common/chrome_version_info_posix.cc',
         'common/chrome_version_info_mac.mm',
         'common/chrome_version_info_win.cc',
         'common/chrome_version_info.h',
         'common/cloud_print/cloud_print_class_mac.h',
@@ skipping 395 matching lines @@
         'common/metrics/proto/user_action_event.proto',
       ],
       'variables': {
         'proto_in_dir': 'common/metrics/proto',
         'proto_out_dir': 'chrome/common/metrics/proto',
       },
       'includes': [ '../build/protoc.gypi' ],
     },
   ],
 }