Pass Callback to TaskRunner by value and consume it on invocation (1)

ios/web/public/web_thread.h

 // 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.
 
 #ifndef IOS_WEB_PUBLIC_WEB_THREAD_H_
 #define IOS_WEB_PUBLIC_WEB_THREAD_H_
 
 #include <string>
 #include <utility>
 
@@ skipping 83 matching lines @@
     // identifier.
     ID_COUNT
   };
 
   // These are the same methods as in message_loop.h, but are guaranteed to
   // either get posted to the MessageLoop if it's still alive, or be deleted
   // otherwise.
   // They return true iff the thread existed and the task was posted.
   static bool PostTask(ID identifier,
                        const tracked_objects::Location& from_here,
-                       const base::Closure& task);
+                       base::Closure task);
   static bool PostDelayedTask(ID identifier,
                               const tracked_objects::Location& from_here,
-                              const base::Closure& task,
+                              base::Closure task,
                               base::TimeDelta delay);
   static bool PostNonNestableTask(ID identifier,
                                   const tracked_objects::Location& from_here,
-                                  const base::Closure& task);
+                                  base::Closure task);
   static bool PostNonNestableDelayedTask(
       ID identifier,
       const tracked_objects::Location& from_here,
-      const base::Closure& task,
+      base::Closure task,
       base::TimeDelta delay);
 
   static bool PostTaskAndReply(ID identifier,
                                const tracked_objects::Location& from_here,
                                base::Closure task,
                                base::Closure reply);
 
   template <typename ReturnType, typename ReplyArgType>
   static bool PostTaskAndReplyWithResult(
       ID identifier,
@@ skipping 28 matching lines @@
   // 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().
   //
   // If you need to PostTaskAndReplyWithResult, use
   // base::PostTaskAndReplyWithResult() with GetBlockingPool() as the task
   // runner.
   static bool PostBlockingPoolTask(const tracked_objects::Location& from_here,
-                                   const base::Closure& task);
+                                   base::Closure task);
   static bool PostBlockingPoolTaskAndReply(
       const tracked_objects::Location& from_here,
       base::Closure task,
       base::Closure reply);
   static bool PostBlockingPoolSequencedTask(
       const std::string& sequence_token_name,
       const tracked_objects::Location& from_here,
-      const base::Closure& task);
+      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.
   static base::SequencedWorkerPool* GetBlockingPool() WARN_UNUSED_RESULT;
 
   // Callable on any thread.  Returns whether the given well-known thread is
   // initialized.
   static bool IsThreadInitialized(ID identifier) WARN_UNUSED_RESULT;
 
   // Callable on any thread.  Returns whether execution is currently on the
@@ skipping 77 matching lines @@
  private:
   friend class WebThreadImpl;
 
   WebThread() {}
   DISALLOW_COPY_AND_ASSIGN(WebThread);
 };
 
 }  // namespace web
 
 #endif  // IOS_WEB_PUBLIC_WEB_THREAD_H_