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

media/base/fake_single_thread_task_runner.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 "media/base/fake_single_thread_task_runner.h"
 
+#include <utility>
+
+#include "base/callback_helpers.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/time/tick_clock.h"
 
 namespace media {
 
 FakeSingleThreadTaskRunner::FakeSingleThreadTaskRunner(
     base::SimpleTestTickClock* clock)
     : clock_(clock), fail_on_next_task_(false) {}
 
 FakeSingleThreadTaskRunner::~FakeSingleThreadTaskRunner() {}
 
 bool FakeSingleThreadTaskRunner::PostDelayedTask(
     const tracked_objects::Location& from_here,
-    const base::Closure& task,
+    base::Closure task,
     base::TimeDelta delay) {
   if (fail_on_next_task_) {
     LOG(FATAL) << "Infinite task posting loop detected.  Possibly caused by "
                << from_here.ToString() << " posting a task with delay "
                << delay.InMicroseconds() << " usec.";
   }
 
   CHECK_LE(base::TimeDelta(), delay);
   const base::TimeTicks run_time = clock_->NowTicks() + delay;
 
   // If there are one or more tasks with the exact same run time, schedule this
   // task to occur after them.  This mimics the FIFO ordering behavior when
   // scheduling delayed tasks to be run via base::MessageLoop in a
   // multi-threaded application.
   if (!tasks_.empty()) {
     const auto after_it = tasks_.lower_bound(
         TaskKey(run_time + base::TimeDelta::FromMicroseconds(1), 0));
     if (after_it != tasks_.begin()) {
       auto it = after_it;
       --it;
       if (it->first.first == run_time) {
-        tasks_.insert(
-            after_it /* hint */,
-            std::make_pair(TaskKey(run_time, it->first.second + 1), task));
+        tasks_.insert(after_it /* hint */,
+                      std::make_pair(TaskKey(run_time, it->first.second + 1),
+                                     std::move(task)));
         return true;
       }
     }
   }
 
   // No tasks have the exact same run time, so just do a simple insert.
-  tasks_.insert(std::make_pair(TaskKey(run_time, 0), task));
+  tasks_.insert(std::make_pair(TaskKey(run_time, 0), std::move(task)));
   return true;
 }
 
 bool FakeSingleThreadTaskRunner::RunsTasksOnCurrentThread() const {
   return true;
 }
 
 void FakeSingleThreadTaskRunner::RunTasks() {
   while (true) {
     // Run all tasks equal or older than current time.
     const auto it = tasks_.begin();
     if (it == tasks_.end())
       return;  // No more tasks.
 
     if (clock_->NowTicks() < it->first.first)
       return;
 
-    const base::Closure task = it->second;
+    base::Closure task = std::move(it->second);
     tasks_.erase(it);
-    task.Run();
+    std::move(task).Run();
   }
 }
 
 void FakeSingleThreadTaskRunner::Sleep(base::TimeDelta t) {
   CHECK_LE(base::TimeDelta(), t);
   const base::TimeTicks run_until = clock_->NowTicks() + t;
 
   while (1) {
     // Run up to 100000 tasks that were scheduled to run during the sleep
     // period. 100000 should be enough for everybody (see comments below).
@@ skipping 14 matching lines @@
     // non-delayed task is being posted every time a task is popped and invoked
     // from the queue. If that happens, set fail_on_next_task_ to true and throw
     // an error when the next task is posted, where we might be able to identify
     // the caller causing the problem via logging.
     fail_on_next_task_ = true;
   }
 }
 
 bool FakeSingleThreadTaskRunner::PostNonNestableDelayedTask(
     const tracked_objects::Location& from_here,
-    const base::Closure& task,
+    base::Closure task,
     base::TimeDelta delay) {
   NOTIMPLEMENTED();
   return false;
 }
 
 }  // namespace media