Move blink scheduler implementation into a component

content/child/scheduler/cancelable_closure_holder.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/scheduler/cancelable_closure_holder.h"
-
-namespace content {
-
-CancelableClosureHolder::CancelableClosureHolder() {
-}
-
-CancelableClosureHolder::~CancelableClosureHolder() {
-}
-
-void CancelableClosureHolder::Reset(const base::Closure& callback) {
-  callback_ = callback;
-  cancelable_callback_.Reset(callback_);
-}
-
-void CancelableClosureHolder::Cancel() {
-  DCHECK(!callback_.is_null());
-  cancelable_callback_.Reset(callback_);
-}
-
-const base::Closure& CancelableClosureHolder::callback() const {
-  DCHECK(!callback_.is_null());
-  return cancelable_callback_.callback();
-}
-
-}  // namespace content