Add BrowserThread::PostBlockingTaskAndReply.

content/public/browser/browser_thread.h

 // 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.
 
 #ifndef CONTENT_PUBLIC_BROWSER_BROWSER_THREAD_H_
 #define CONTENT_PUBLIC_BROWSER_BROWSER_THREAD_H_
 #pragma once
 
 #include <string>
 
@@ skipping 136 matching lines @@
                           const tracked_objects::Location& from_here,
                           const T* object) {
     return GetMessageLoopProxyForThread(identifier)->ReleaseSoon(
         from_here, object);
   }
 
   // Simplified wrappers for posting to the blocking thread pool. Use this
   // for doing things like blocking I/O.
   //
   // The first variant will run the task in the pool with no sequencing
-  // semantics, so may get run in parallel with other posted tasks. The
-  // second variant provides sequencing between tasks with the same
-  // sequence token name.
+  // semantics, so may get run in parallel with other posted tasks. The second
+  // variant will all post a task with no sequencing semantics, and will post a
+  // reply task to the origin TaskRunner upon completion.  The third variant
+  // provides sequencing between tasks with the same sequence token name.
   //
   // These tasks are guaranteed to run before shutdown.
   //
   // If you need to provide different shutdown semantics (like you have
   // something slow and noncritical that doesn't need to block shutdown),
   // or you want to manually provide a sequence token (which saves a map
   // lookup and is guaranteed unique without you having to come up with a
   // unique string), you can access the sequenced worker pool directly via
   // GetBlockingPool().
   static bool PostBlockingPoolTask(const tracked_objects::Location& from_here,
                                    const base::Closure& task);
+  static bool PostBlockingPoolTaskAndReply(
+      const tracked_objects::Location& from_here,
+      const base::Closure& task,
+      const base::Closure& reply);
   static bool PostBlockingPoolSequencedTask(
       const std::string& sequence_token_name,
       const tracked_objects::Location& from_here,
       const base::Closure& task);
 
   // Returns the thread pool used for blocking file I/O. Use this object to
   // perform random blocking operations such as file writes or querying the
   // Windows registry.
   static base::SequencedWorkerPool* GetBlockingPool();
 
@@ skipping 84 matching lines @@
  private:
   friend class BrowserThreadImpl;
 
   BrowserThread() {}
   DISALLOW_COPY_AND_ASSIGN(BrowserThread);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_BROWSER_THREAD_H_