Simplify checking for prefetch field trial in RDH

chrome/browser/renderer_host/chrome_resource_dispatcher_host_delegate.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 "chrome/browser/renderer_host/chrome_resource_dispatcher_host_delegate.h"
 
 #include <stdint.h>
 #include <string>
 #include <utility>
 #include <vector>
 
 #include "base/base64.h"
 #include "base/guid.h"
 #include "base/logging.h"
+#include "base/metrics/field_trial.h"
+#include "base/strings/string_util.h"
 #include "build/build_config.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/component_updater/component_updater_resource_throttle.h"
 #include "chrome/browser/download/download_request_limiter.h"
 #include "chrome/browser/download/download_resource_throttle.h"
 #include "chrome/browser/mod_pagespeed/mod_pagespeed_metrics.h"
 #include "chrome/browser/net/resource_prefetch_predictor_observer.h"
 #include "chrome/browser/plugins/plugin_prefs.h"
-#include "chrome/browser/prefetch/prefetch.h"
 #include "chrome/browser/prerender/prerender_manager.h"
 #include "chrome/browser/prerender/prerender_manager_factory.h"
 #include "chrome/browser/prerender/prerender_resource_throttle.h"
 #include "chrome/browser/prerender/prerender_util.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/profiles/profile_io_data.h"
 #include "chrome/browser/renderer_host/safe_browsing_resource_throttle.h"
 #include "chrome/browser/renderer_host/thread_hop_resource_throttle.h"
 #include "chrome/browser/safe_browsing/safe_browsing_service.h"
 #include "chrome/browser/signin/chrome_signin_helper.h"
@@ skipping 255 matching lines @@
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
 
   // Handle a PREFETCH resource type. If prefetch is disabled, squelch the
   // request.  Otherwise, do a normal request to warm the cache.
   if (resource_type == content::RESOURCE_TYPE_PREFETCH) {
     // All PREFETCH requests should be GETs, but be defensive about it.
     if (method != "GET")
       return false;
 
     // If prefetch is disabled, kill the request.
-    if (!prefetch::IsPrefetchEnabled(resource_context))
+    std::string prefetch_experiment =
+        base::FieldTrialList::FindFullName("Prefetch");
+    if (base::StartsWith(prefetch_experiment, "ExperimentDisable",
+                         base::CompareCase::INSENSITIVE_ASCII)) {
       return false;
+    }
   }
 
   return true;
 }
 
 void ChromeResourceDispatcherHostDelegate::RequestBeginning(
     net::URLRequest* request,
     content::ResourceContext* resource_context,
     content::AppCacheService* appcache_service,
     ResourceType resource_type,
@@ skipping 397 matching lines @@
     return data_reduction_proxy_io_data->ShouldEnableLoFiMode(url_request);
   return false;
 }
 
 // static
 void ChromeResourceDispatcherHostDelegate::
     SetExternalProtocolHandlerDelegateForTesting(
     ExternalProtocolHandler::Delegate* delegate) {
   g_external_protocol_handler_delegate = delegate;
 }