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

base/critical_closure.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 BASE_CRITICAL_CLOSURE_H_
 #define BASE_CRITICAL_CLOSURE_H_
 
+#include <utility>
+
 #include "base/callback.h"
 #include "base/macros.h"
 #include "build/build_config.h"
 
 #if defined(OS_IOS)
 #include "base/bind.h"
 #include "base/ios/scoped_critical_action.h"
 #endif
 
 namespace base {
 
 namespace internal {
 
 #if defined(OS_IOS)
 // Returns true if multi-tasking is supported on this iOS device.
 bool IsMultiTaskingSupported();
 
 // This class wraps a closure so it can continue to run for a period of time
 // when the application goes to the background by using
 // |ios::ScopedCriticalAction|.
 class CriticalClosure {
  public:
-  explicit CriticalClosure(const Closure& closure);
+  explicit CriticalClosure(Closure closure);
   ~CriticalClosure();
   void Run();
 
  private:
   ios::ScopedCriticalAction critical_action_;
   Closure closure_;
 
   DISALLOW_COPY_AND_ASSIGN(CriticalClosure);
 };
 #endif  // defined(OS_IOS)
 
 }  // namespace internal
 
 // Returns a closure that will continue to run for a period of time when the
 // application goes to the background if possible on platforms where
 // applications don't execute while backgrounded, otherwise the original task is
 // returned.
 //
 // Example:
 //   file_task_runner_->PostTask(
 //       FROM_HERE,
 //       MakeCriticalClosure(base::Bind(&WriteToDiskTask, path_, data)));
 //
 // Note new closures might be posted in this closure. If the new closures need
 // background running time, |MakeCriticalClosure| should be applied on them
 // before posting.
 #if defined(OS_IOS)
-inline Closure MakeCriticalClosure(const Closure& closure) {
+inline Closure MakeCriticalClosure(Closure closure) {
   DCHECK(internal::IsMultiTaskingSupported());
   return base::Bind(&internal::CriticalClosure::Run,
-                    Owned(new internal::CriticalClosure(closure)));
+                    Owned(new internal::CriticalClosure(std::move(closure))));
 }
 #else  // defined(OS_IOS)
-inline Closure MakeCriticalClosure(const Closure& closure) {
+inline Closure MakeCriticalClosure(Closure closure) {
   // No-op for platforms where the application does not need to acquire
   // background time for closures to finish when it goes into the background.
   return closure;
 }
 #endif  // defined(OS_IOS)
 
 }  // namespace base
 
 #endif  // BASE_CRITICAL_CLOSURE_H_