Add a field trial to disable deferred committing of cookie changes

chrome/browser/prerender/prerender_contents.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/prerender/prerender_contents.h"
 
 #include <algorithm>
 #include <functional>
 #include <utility>
 
@@ skipping 332 matching lines @@
   alias_session_storage_namespace->AddTransactionLogProcessId(child_id_);
 
   // Add the RenderProcessHost to the Prerender Manager.
   prerender_manager()->AddPrerenderProcessHost(
       GetRenderViewHost()->GetProcess());
 
   // In the prerender tracker, create a Prerender Cookie Store to keep track of
   // cookie changes performed by the prerender. Once the prerender is shown,
   // the cookie changes will be committed to the actual cookie store,
   // otherwise, they will be discarded.
-  BrowserThread::PostTask(
-      BrowserThread::IO, FROM_HERE,
-      base::Bind(&PrerenderTracker::AddPrerenderCookieStoreOnIOThread,
-                 base::Unretained(prerender_manager()->prerender_tracker()),
-                 GetRenderViewHost()->GetProcess()->GetID(),
-                 make_scoped_refptr(request_context),
-                 base::Bind(&PrerenderContents::Destroy,
-                            AsWeakPtr(),
-                            FINAL_STATUS_COOKIE_CONFLICT)));
+  // If |request_context| is NULL, the feature must be disabled, so the
+  // operation will not be performed.
+  if (request_context) {
+    BrowserThread::PostTask(
+        BrowserThread::IO, FROM_HERE,
+        base::Bind(&PrerenderTracker::AddPrerenderCookieStoreOnIOThread,
+                   base::Unretained(prerender_manager()->prerender_tracker()),
+                   GetRenderViewHost()->GetProcess()->GetID(),
+                   make_scoped_refptr(request_context),
+                   base::Bind(&PrerenderContents::Destroy,
+                              AsWeakPtr(),
+                              FINAL_STATUS_COOKIE_CONFLICT)));
+  }
 
   NotifyPrerenderStart();
 
   // Close ourselves when the application is shutting down.
   notification_registrar_.Add(this, chrome::NOTIFICATION_APP_TERMINATING,
                               content::NotificationService::AllSources());
 
   // Register to inform new RenderViews that we're prerendering.
   notification_registrar_.Add(
       this, content::NOTIFICATION_WEB_CONTENTS_RENDER_VIEW_HOST_CREATED,
@@ skipping 527 matching lines @@
  void PrerenderContents::AddResourceThrottle(
      const base::WeakPtr<PrerenderResourceThrottle>& throttle) {
    resource_throttles_.push_back(throttle);
  }
 
  void PrerenderContents::AddNetworkBytes(int64 bytes) {
    network_bytes_ += bytes;
  }
 
 }  // namespace prerender