Make the browser->metro_viewer IPC channel name a constant instead of hardcoding it in a few places…

win8/metro_driver/metro_driver.gyp

 # 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.
 {
   'conditions': [
     ['OS=="win"', {
       'variables': {
         'chromium_code': 1,
       },
       'includes': [
@@ skipping 54 matching lines @@
           'sources': [
             'metro_driver.cc',
             'metro_driver.h',
             'stdafx.h',
             'winrt_utils.cc',
             'winrt_utils.h',
             '<(SHARED_INTERMEDIATE_DIR)/metro_driver/metro_driver_dll_version.rc',
           ],
           'conditions': [
             ['use_aura==1', {
+              'dependencies': [
+                '../win8.gyp:metro_viewer',
+              ],
               'sources': [
                 'chrome_app_view_ash.cc',
                 'chrome_app_view_ash.h',
                 'direct3d_helper.cc',
                 'direct3d_helper.h',
                 'file_picker_ash.cc',
                 'file_picker_ash.h',
               ],
             }, {  # use_aura!=1
               'sources': [
@@ skipping 47 matching lines @@
             'run_all_unittests.cc',
             'winrt_utils.cc',
             'winrt_utils.h',
             'winrt_utils_unittest.cc',
           ],
         },
       ],
     },],
   ],
 }