scheduler: Implement task observers

content/renderer/scheduler/webthread_impl_for_scheduler.h

+// Copyright 2015 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 CONTENT_RENDERER_SCHEDULER_WEBTHREAD_IMPL_FOR_SCHEDULER_H_
+#define CONTENT_RENDERER_SCHEDULER_WEBTHREAD_IMPL_FOR_SCHEDULER_H_
+
+#include "content/child/webthread_impl.h"
+
+namespace content {
+
+class RendererScheduler;
+
+class WebThreadImplForScheduler : public WebThreadBase {
+ public:
+  CONTENT_EXPORT explicit WebThreadImplForScheduler(
+      RendererScheduler* scheduler);
+  CONTENT_EXPORT virtual ~WebThreadImplForScheduler();
+
+  virtual void postTask(const blink::WebTraceLocation& location, Task* task);

[alex clarke (OOO till 29th), 2015/02/13 11:02:07]

Maybe add a comment above on the lines of: implements blink::WebThread

[Sami, 2015/02/13 12:09:09]

Done.

+  virtual void postDelayedTask(const blink::WebTraceLocation& location,
+                               Task* task,
+                               long long delay_ms);
+
+  // TODO(skyostil): Remove once blink has migrated.
+  virtual void postTask(Task* task);
+  virtual void postDelayedTask(Task* task, long long delay_ms);
+
+  virtual void enterRunLoop() override;

[alex clarke (OOO till 29th), 2015/02/13 11:02:07]

nit: only one of virtual & override

[Sami, 2015/02/13 12:09:09]

Well spotted. I'll keep this is virtual instead of override since the base class
comes from Blink.

+  virtual void exitRunLoop() override;
+
+  virtual bool isCurrentThread() const override;

[alex clarke (OOO till 29th), 2015/02/13 11:02:07]

Maybe add a comment above on the lines of: implements WebThreadBase

[Sami, 2015/02/13 12:09:09]

Actually these also part of blink::WebThread. I've got a patch here that cleans
some of this up but I wanted to split it out to make this review clearer:
https://codereview.chromium.org/923973002

+  virtual blink::PlatformThreadId threadId() const override;
+
+ private:
+  void AddTaskObserverInternal(
+      base::MessageLoop::TaskObserver* observer) override;
+  void RemoveTaskObserverInternal(
+      base::MessageLoop::TaskObserver* observer) override;
+
+  scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
+  RendererScheduler* scheduler_;  // Not owned.
+  blink::PlatformThreadId thread_id_;
+};
+
+}  // namespace content
+
+#endif  // CONTENT_RENDERER_SCHEDULER_WEBTHREAD_IMPL_FOR_SCHEDULER_H_