content: Add RendererScheduler.

content/renderer/scheduler/renderer_scheduler.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_RENDERER_SCHEDULER_H_
+#define CONTENT_RENDERER_SCHEDULER_RENDERER_SCHEDULER_H_
+
+#include "base/atomicops.h"
+#include "base/task/task_queue_manager.h"
+#include "base/threading/thread_checker.h"
+
+namespace cc {
+struct BeginFrameArgs;
+}
+
+namespace content {
+
+class RendererSchedulerSelector;
+
+class RendererScheduler {
+ public:
+  enum QueueId {
+    kDefaultTaskQueue,
+    kCompositorTaskQueue,
+    kIdleTaskQueue,
+    // Must be the last entry.
+    kTaskQueueCount,
+  };
+
+  RendererScheduler();
+  ~RendererScheduler();
+
+  // Returns the task runner which targets the queue selected by |queue_index|.
+  scoped_refptr<base::SingleThreadTaskRunner> TaskRunnerForQueue(QueueId queue);
+
+  // Called to notify about the start of a new frame.  Must be called from the
+  // main thread.
+  void WillBeginFrame(const cc::BeginFrameArgs& args);
+
+  // Called to notify that a previously begun frame was committed. Must be
+  // called from the main thread.
+  void DidCommitFrameToCompositor();
+
+  // Tells the scheduler that the system received an input event. Can be called
+  // on any thread.
+  void DidReceiveInputEvent();
+
+  // Returns true if there is high priority work pending on the main thread
+  // and the caller should yield to let the scheduler service that work.
+  // Can be called on any thread.
+  bool ShouldYieldForHighPriorityWork();
+
+  // Returns the deadline by which an idle task should finish by for the
+  // current frame. Must be called from the main thread.
+  base::TimeTicks CurrentFrameDeadlineForIdleTasks() const;
+
+ private:
+  enum Policy {
+    kNormalPriorityPolicy,
+    kCompositorPriorityPolicy,
+  };
+
+  size_t kControlQueue = kTaskQueueCount;
+  size_t kTaskAndControlQueueCount = kControlQueue + 1;
+

[picksi1, 2014/10/20 11:42:04]

Why are these not part of the enum?

[rmcilroy, 2014/10/21 17:21:27]

Because they are not public (I don't want someone calling
TaskRunnerForQueue(kControlQueue) and being able to run control level tasks
since these should only be posted by the scheduler.

+  // The time we should stay in CompositorPriority mode for after a touch event.
+  base::TimeDelta kCompositoryPriorityAfterTouchTime =
+      base::TimeDelta::FromMilliseconds(100);
+
+  // Returns the current scheduler policy. Can be called on any thread.
+  Policy SchedulerPolicy() const;
+
+  // Enters the scheduler policy. Must be called from the main thread.
+  void EnterSchedulerPolicy(Policy policy);
+
+  // Start and end an idle period.
+  void StartIdlePeriod();
+  void EndIdlePeriod();
+
+  base::ThreadChecker main_thread_checker_;
+  scoped_ptr<RendererSchedulerSelector> renderer_scheduler_selector_;
+  base::TaskQueueManager task_queue_manager_;
+  scoped_refptr<base::SingleThreadTaskRunner> control_task_runner_;
+
+  // Don't access scheduler_policy_ directly, use EnterSchedulerPolicy
+  // and SchedulerPolicy instead.
+  base::subtle::AtomicWord current_policy_;
+
+  base::TimeTicks estimated_next_frame_begin_;
+};
+
+}  // namespace content
+
+#endif  // CONTENT_RENDERER_SCHEDULER_RENDERER_SCHEDULER_H_