Adds a CancellableTaskFactory and exposes postLoadingTasks to Blink

Source/platform/scheduler/Scheduler.cpp

 // 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 "config.h"
 #include "platform/scheduler/Scheduler.h"
 
 #include "platform/TraceLocation.h"
 #include "public/platform/Platform.h"
 #include "public/platform/WebScheduler.h"
 #include "public/platform/WebTraceLocation.h"
 
 namespace blink {
 
 class IdleTaskRunner : public WebScheduler::IdleTask {
+    WTF_MAKE_NONCOPYABLE(IdleTaskRunner);
+
 public:
     explicit IdleTaskRunner(PassOwnPtr<Scheduler::IdleTask> task)
         : m_task(task)
     {
     }
 
-    virtual ~IdleTaskRunner()
+    ~IdleTaskRunner() override
     {
     }
 
     // WebScheduler::IdleTask implementation.
     void run(double deadlineSeconds) override
     {
         (*m_task)(deadlineSeconds);
     }
 private:
     OwnPtr<Scheduler::IdleTask> m_task;
@@ skipping 24 matching lines @@
     if (m_webScheduler)
         m_webScheduler->shutdown();
 }
 
 void Scheduler::postIdleTask(const TraceLocation& location, PassOwnPtr<IdleTask> idleTask)
 {
     if (m_webScheduler)
         m_webScheduler->postIdleTask(WebTraceLocation(location), new IdleTaskRunner(idleTask));
 }
 
+void Scheduler::postLoadingTask(const TraceLocation& location, WebThread::Task* task)
+{
+    if (m_webScheduler)
+        m_webScheduler->postLoadingTask(WebTraceLocation(location), task);
+}
+
 bool Scheduler::shouldYieldForHighPriorityWork() const
 {
     if (m_webScheduler)
         return m_webScheduler->shouldYieldForHighPriorityWork();
     return false;
 }
 
 } // namespace blink