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

content/child/worker_thread_registry.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 "content/child/worker_thread_registry.h"
 
 #include <memory>
+#include <utility>
 
-#include "base/callback.h"
 #include "base/lazy_instance.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/observer_list.h"
 #include "base/single_thread_task_runner.h"
 #include "base/stl_util.h"
 #include "base/threading/thread_local.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "content/public/child/worker_thread.h"
 
@@ skipping 11 matching lines @@
 
 // A task-runner that refuses to run any tasks.
 class DoNothingTaskRunner : public base::TaskRunner {
  public:
   DoNothingTaskRunner() {}
 
  private:
   ~DoNothingTaskRunner() override {}
 
   bool PostDelayedTask(const tracked_objects::Location& from_here,
-                       const base::Closure& task,
+                       base::Closure task,
                        base::TimeDelta delay) override {
     return false;
   }
 
   bool RunsTasksOnCurrentThread() const override { return false; }
 };
 
 }  // namespace
 
 // WorkerThread implementation:
 
 int WorkerThread::GetCurrentId() {
   if (!g_observers_tls.Pointer()->Get())
     return 0;
   return base::PlatformThread::CurrentId();
 }
 
-void WorkerThread::PostTask(int id, const base::Closure& task) {
-  WorkerThreadRegistry::Instance()->PostTask(id, task);
+void WorkerThread::PostTask(int id, base::Closure task) {
+  WorkerThreadRegistry::Instance()->PostTask(id, std::move(task));
 }
 
 void WorkerThread::AddObserver(Observer* observer) {
   DCHECK(GetCurrentId() > 0);
   WorkerThreadObservers* observers = g_observers_tls.Pointer()->Get();
   DCHECK(observers);
   observers->AddObserver(observer);
 }
 
 void WorkerThread::RemoveObserver(Observer* observer) {
   DCHECK(GetCurrentId() > 0);
   WorkerThreadObservers* observers = g_observers_tls.Pointer()->Get();
   DCHECK(observers);
   observers->RemoveObserver(observer);
 }
 
 // WorkerThreadRegistry implementation:
 
 WorkerThreadRegistry::WorkerThreadRegistry()
     : task_runner_for_dead_worker_(new DoNothingTaskRunner()) {}
 
-int WorkerThreadRegistry::PostTaskToAllThreads(const base::Closure& closure) {
+int WorkerThreadRegistry::PostTaskToAllThreads(base::Closure closure) {
   base::AutoLock locker(task_runner_map_lock_);
   for (const auto& it : task_runner_map_)
-    it.second->PostTask(FROM_HERE, closure);
+    it.second->PostTask(FROM_HERE, std::move(closure));
   return static_cast<int>(task_runner_map_.size());
 }
 
 WorkerThreadRegistry* WorkerThreadRegistry::Instance() {
   static base::LazyInstance<WorkerThreadRegistry>::Leaky worker_task_runner =
       LAZY_INSTANCE_INITIALIZER;
   return worker_task_runner.Pointer();
 }
 
 WorkerThreadRegistry::~WorkerThreadRegistry() {}
@@ skipping 22 matching lines @@
   g_observers_tls.Pointer()->Set(nullptr);
 }
 
 base::TaskRunner* WorkerThreadRegistry::GetTaskRunnerFor(int worker_id) {
   base::AutoLock locker(task_runner_map_lock_);
   return base::ContainsKey(task_runner_map_, worker_id)
              ? task_runner_map_[worker_id]
              : task_runner_for_dead_worker_.get();
 }
 
-bool WorkerThreadRegistry::PostTask(int id, const base::Closure& closure) {
+bool WorkerThreadRegistry::PostTask(int id, base::Closure closure) {
   DCHECK(id > 0);
   base::AutoLock locker(task_runner_map_lock_);
   IDToTaskRunnerMap::iterator found = task_runner_map_.find(id);
   if (found == task_runner_map_.end())
     return false;
-  return found->second->PostTask(FROM_HERE, closure);
+  return found->second->PostTask(FROM_HERE, std::move(closure));
 }
 
 }  // namespace content