Forward input tasks to the Blink scheduler

content/renderer/scheduler_proxy_task_runner.h

+// 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.
+
+#ifndef CONTENT_RENDERER_SCHEDULER_PROXY_TASK_RUNNER_H_
+#define CONTENT_RENDERER_SCHEDULER_PROXY_TASK_RUNNER_H_
+
+#include "base/debug/task_annotator.h"
+#include "base/pending_task.h"
+#include "content/renderer/render_thread_impl.h"
+#include "third_party/WebKit/public/platform/WebSchedulerProxy.h"
+#include "third_party/WebKit/public/platform/WebTraceLocation.h"
+
+namespace content {
+
+// Helper for forwarding posted tasks into different WebSchedulerProxy queues.
+template <void (blink::WebSchedulerProxy::*ProxyFunction)(
+    const blink::WebTraceLocation& location,
+    blink::WebThread::Task* task)>
+class SchedulerProxyTaskRunner : public base::SingleThreadTaskRunner {
+ public:
+  SchedulerProxyTaskRunner()
+      : main_thread_id_(base::PlatformThread::CurrentId()),
+        scheduler_proxy_(blink::WebSchedulerProxy::create()),
+        next_sequence_num_(0) {}
+
+  // base::SingleThreadTaskRunner implementation:
+  virtual bool RunsTasksOnCurrentThread() const OVERRIDE {
+    return base::PlatformThread::CurrentId() == main_thread_id_;
+  }
+
+  virtual bool PostDelayedTask(const tracked_objects::Location& from_here,
+                               const base::Closure& task,
+                               base::TimeDelta delay) OVERRIDE {
+    DCHECK(delay == base::TimeDelta());
+    base::PendingTask pending_task(from_here, task);
+    pending_task.sequence_num = ++next_sequence_num_;
+    task_annotator_.DidQueueTask("SchedulerProxyTaskRunner::PostDelayedTask",
+                                 pending_task);
+    blink::WebTraceLocation location(from_here.function_name(),
+                                     from_here.file_name());
+    TaskAdapter* task_adapter = new TaskAdapter(&task_annotator_, pending_task);
+    (scheduler_proxy_.*ProxyFunction)(location, task_adapter);
+    return true;
+  }
+
+  virtual bool PostNonNestableDelayedTask(
+      const tracked_objects::Location& from_here,
+      const base::Closure& task,
+      base::TimeDelta delay) OVERRIDE {
+    NOTREACHED();
+    return false;
+  }
+
+ protected:
+  virtual ~SchedulerProxyTaskRunner() {}
+
+ private:
+  class TaskAdapter : public blink::WebThread::Task {
+   public:
+    explicit TaskAdapter(base::debug::TaskAnnotator* task_annotator,
+                         const base::PendingTask& pending_task)
+        : task_annotator_(task_annotator), pending_task_(pending_task) {}
+    virtual ~TaskAdapter() {}
+
+    virtual void run() {
+      task_annotator_->RunTask("SchedulerProxyTaskRunner::PostDelayedTask",
+                               "SchedulerProxyTaskRunner::RunTask",
+                               pending_task_);
+    }
+
+   private:
+    base::debug::TaskAnnotator* task_annotator_;
+    base::PendingTask pending_task_;
+  };
+
+  const base::PlatformThreadId main_thread_id_;
+  blink::WebSchedulerProxy scheduler_proxy_;
+  base::debug::TaskAnnotator task_annotator_;
+  int next_sequence_num_;
+
+  DISALLOW_COPY_AND_ASSIGN(SchedulerProxyTaskRunner);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_RENDERER_SCHEDULER_PROXY_TASK_RUNNER_H_