Add trace-viewer to third party and redirect about:tracing to that implementation.

chrome/chrome_repack_chrome.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.
 {
   'action_name': 'repack_chrome',
   'variables': {
     'pak_inputs': [
       '<(grit_out_dir)/browser_resources.pak',
       '<(grit_out_dir)/common_resources.pak',
       '<(grit_out_dir)/renderer_resources.pak',
       '<(grit_out_dir)/theme_resources.pak',
+      '<(grit_out_dir)/tracing_resources.pak',
       '<(SHARED_INTERMEDIATE_DIR)/content/content_resources.pak',
       '<(SHARED_INTERMEDIATE_DIR)/net/net_resources.pak',
       '<(SHARED_INTERMEDIATE_DIR)/ui/ui_resources/ui_resources.pak',
       '<(SHARED_INTERMEDIATE_DIR)/webkit/webkit_chromium_resources.pak',
       '<(SHARED_INTERMEDIATE_DIR)/webkit/webkit_resources.pak',
     ],
     'conditions': [
       ['enable_extensions==1', {
         'pak_inputs': [
           '<(grit_out_dir)/extensions_api_resources.pak',
         ],
       }],
     ],
   },
   'inputs': [
     '<(repack_path)',
     '<@(pak_inputs)',
   ],
   'outputs': [
     '<(SHARED_INTERMEDIATE_DIR)/repack/chrome.pak',
   ],
   'action': ['python', '<(repack_path)', '<@(_outputs)', '<@(pak_inputs)'],
 }