Prefetch must not run on cellular until the user can disable

chrome/browser/prefetch/prefetch.cc

 // 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.
 
 #include "chrome/browser/prefetch/prefetch.h"
 
 #include <string>
 
 #include "base/metrics/field_trial.h"
 #include "base/strings/string_util.h"
 #include "chrome/browser/net/prediction_options.h"
 #include "chrome/browser/prefetch/prefetch_field_trial.h"
 #include "chrome/browser/profiles/profile_io_data.h"
 #include "net/base/network_change_notifier.h"
 
 namespace prefetch {
 
 bool IsPrefetchEnabled(content::ResourceContext* resource_context) {
   DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::IO));
 
   ProfileIOData* io_data = ProfileIOData::FromResourceContext(resource_context);
+  DCHECK(io_data);
 
-  DCHECK(io_data);
+  // TODO(bnc): Remove this condition once the new
+  // predictive preference is used on all platforms. See crbug.com/334602.
+  if (io_data->network_prediction_options()->GetValue() ==
+          chrome_browser_net::NETWORK_PREDICTION_UNSET &&
+      net::NetworkChangeNotifier::IsConnectionCellular(
+          net::NetworkChangeNotifier::GetConnectionType())) {
+    return false;
+  }
 
   return chrome_browser_net::CanPredictNetworkActionsIO(io_data) &&
          !DisableForFieldTrial();
 }
 
 }  // namespace prefetch