Update from https://crrev.com/304418

net/url_request/url_request_context_builder.cc

 // 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.
 
 #include "net/url_request/url_request_context_builder.h"
 
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
@@ skipping 196 matching lines @@
 
 URLRequestContextBuilder::URLRequestContextBuilder()
     : data_enabled_(false),
 #if !defined(DISABLE_FILE_SUPPORT)
       file_enabled_(false),
 #endif
 #if !defined(DISABLE_FTP_SUPPORT)
       ftp_enabled_(false),
 #endif
       http_cache_enabled_(true),
-      throttling_enabled_(false) {
+      throttling_enabled_(false),
+      channel_id_enabled_(true) {
 }
 
 URLRequestContextBuilder::~URLRequestContextBuilder() {}
 
 void URLRequestContextBuilder::EnableHttpCache(const HttpCacheParams& params) {
   http_cache_enabled_ = true;
   http_cache_params_ = params;
 }
 
 void URLRequestContextBuilder::DisableHttpCache() {
@@ skipping 61 matching lines @@
       net::HttpAuthHandlerRegistryFactory::CreateDefault(
            context->host_resolver());
   for (size_t i = 0; i < extra_http_auth_handlers_.size(); ++i) {
     http_auth_handler_registry_factory->RegisterSchemeFactory(
         extra_http_auth_handlers_[i].scheme,
         extra_http_auth_handlers_[i].factory);
   }
   storage->set_http_auth_handler_factory(http_auth_handler_registry_factory);
   storage->set_cookie_store(new CookieMonster(NULL, NULL));
 
-  // TODO(mmenke):  This always creates a file thread, even when it ends up
-  // not being used.  Consider lazily creating the thread.
-  storage->set_channel_id_service(
-      new ChannelIDService(
-          new DefaultChannelIDStore(NULL),
-          context->GetFileThread()->message_loop_proxy()));
+  if (channel_id_enabled_) {
+    // TODO(mmenke):  This always creates a file thread, even when it ends up
+    // not being used.  Consider lazily creating the thread.
+    storage->set_channel_id_service(
+        new ChannelIDService(
+            new DefaultChannelIDStore(NULL),
+            context->GetFileThread()->message_loop_proxy()));
+  }
 
   storage->set_transport_security_state(new net::TransportSecurityState());
   if (!transport_security_persister_path_.empty()) {
     context->set_transport_security_persister(
         make_scoped_ptr<TransportSecurityPersister>(
             new TransportSecurityPersister(
                 context->transport_security_state(),
                 transport_security_persister_path_,
                 context->GetFileThread()->message_loop_proxy(),
                 false)));
@@ skipping 88 matching lines @@
 #endif  // !defined(DISABLE_FTP_SUPPORT)
 
   storage->set_job_factory(job_factory);
 
   // TODO(willchan): Support sdch.
 
   return context;
 }
 
 }  // namespace net