Fix crashes in DownloadRequestLimiter when extension popups/bubbles initiate downloads automatically

chrome/chrome_browser.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': 'browser',
       'type': 'static_library',
@@ skipping 953 matching lines @@
         'browser/download/download_item_model.cc',
         'browser/download/download_item_model.h',
         'browser/download/download_prefs.cc',
         'browser/download/download_prefs.h',
         'browser/download/download_query.cc',
         'browser/download/download_query.h',
         'browser/download/download_request_infobar_delegate.cc',
         'browser/download/download_request_infobar_delegate.h',
         'browser/download/download_request_limiter.cc',
         'browser/download/download_request_limiter.h',
-        'browser/download/download_request_limiter_observer.cc',
-        'browser/download/download_request_limiter_observer.h',
         'browser/download/download_service.cc',
         'browser/download/download_service.h',
         'browser/download/download_service_factory.cc',
         'browser/download/download_service_factory.h',
         'browser/download/download_danger_prompt.cc',
         'browser/download/download_danger_prompt.h',
         'browser/download/download_shelf.h',
         'browser/download/download_shelf.cc',
         'browser/download/download_shelf_context_menu.cc',
         'browser/download/download_shelf_context_menu.h',
@@ skipping 4118 matching lines @@
         'browser/metrics/proto/study.proto',
       ],
       'variables': {
         'proto_in_dir': 'browser/metrics/proto',
         'proto_out_dir': 'chrome/browser/metrics/proto',
       },
       'includes': [ '../build/protoc.gypi' ]
     },
   ],
 }