Add ScopedAllowIO in WebrtcTransport when shutting down WebRTC session.

PRESUBMIT.py

 # 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.
 
 """Top-level presubmit script for Chromium.
 
 See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
 for more details about the presubmit API built into depot_tools.
 """
 
@@ skipping 198 matching lines @@
         r"^content[\\\/]test[\\\/]ppapi[\\\/]ppapi_test\.cc$",
         r"^mojo[\\\/]edk[\\\/]embedder[\\\/]" +
             r"simple_platform_shared_buffer_posix\.cc$",
         r"^net[\\\/]disk_cache[\\\/]cache_util\.cc$",
         r"^net[\\\/]cert[\\\/]test_root_certs\.cc$",
         r"^net[\\\/]test[\\\/]embedded_test_server[\\\/]" +
             r"embedded_test_server\.cc$",
         r"^net[\\\/]test[\\\/]spawned_test_server[\\\/]local_test_server\.cc$",
         r"^net[\\\/]test[\\\/]test_data_directory\.cc$",
         r"^net[\\\/]url_request[\\\/]test_url_fetcher_factory\.cc$",
+        r"^remoting[\\\/]protocol[\\\/]webrtc_transport\.cc$",
         r"^ui[\\\/]base[\\\/]material_design[\\\/]"
             "material_design_controller\.cc$",
         r"^ui[\\\/]gl[\\\/]init[\\\/]gl_initializer_mac\.cc$",
         r"^ui[\\\/]gl[\\\/]init[\\\/]gl_initializer_win\.cc$",
         r"^ui[\\\/]gl[\\\/]init[\\\/]gl_initializer_x11\.cc$",
         r"^ui[\\\/]ozone[\\\/]platform[\\\/]drm[\\\/]host[\\\/]"
             "drm_display_host_manager\.cc$",
       ),
     ),
     (
@@ skipping 2092 matching lines @@
   results.extend(input_api.canned_checks.CheckTreeIsOpen(
       input_api,
       output_api,
       json_url='http://chromium-status.appspot.com/current?format=json'))
 
   results.extend(input_api.canned_checks.CheckChangeHasBugField(
       input_api, output_api))
   results.extend(input_api.canned_checks.CheckChangeHasDescription(
       input_api, output_api))
   return results