CrNet: add pauseable NSURLProtocol and switch to using it

ios/crnet/crnet_consumer/crnet_consumer.gyp

 # Copyright 2014 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.
 
 {
   'variables': {
     'chromium_code': 1,
   },
   'targets': [],
   'conditions': [
     # Our shared library hack only works with ninja; xcode cannot generate
     # iOS build targets for dynamic libraries.
     ['"<(GENERATOR)"=="ninja"', {
       'targets': [
         {
           'target_name': 'crnet_consumer',
           'type': 'executable',
           'mac_bundle': 1,
           'dependencies': [
             '../../../ios/crnet/crnet_pack.gyp:crnet_pack',
           ],
           'sources': [
             'crnet_consumer_app_delegate.h',
             'crnet_consumer_app_delegate.mm',
             'crnet_consumer_view_controller.h',
             'crnet_consumer_view_controller.m',
-            'main.m',
+            'main.mm',
           ],
           'mac_bundle_resources': [
             '../../../third_party/icu/source/data/in/icudtl.dat',
             'Default.png',
             'crnet-consumer-Info.plist',
           ],
           'include_dirs': [
             '../../..',
             '..',
           ],
@@ skipping 16 matching lines @@
           'xcode_settings': {
             'CLANG_ENABLE_OBJC_ARC': 'YES',
             'DEAD_CODE_STRIPPING': 'YES',
             'INFOPLIST_FILE': 'crnet-consumer-Info.plist',
           },
         },
       ],
     }],
   ],
 }