Add DisplayScheduler to enable BeginFrame-based scheduling of surfaces.

cc/surfaces/display_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 CC_SURFACES_DISPLAY_SCHEDULER_H_
+#define CC_SURFACES_DISPLAY_SCHEDULER_H_
+
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/single_thread_task_runner.h"
+#include "cc/base/rolling_time_delta_history.h"
+#include "cc/scheduler/begin_frame_source.h"
+#include "cc/surfaces/display.h"
+#include "cc/surfaces/surfaces_export.h"
+
+namespace cc {
+

[mithro-old, 2015/03/11 04:19:25]

If we writing a new scheduler, I think we should take some time to design a
proper scheduler rather than the mess of a dependency manager masquerading as a
scheduler at the moment. This class seems to be quickly going down the same
route as the current scheduler.

+class CC_SURFACES_EXPORT DisplayScheduler : public BeginFrameObserver {

[mithro-old, 2015/03/11 04:19:25]

You should probably inherit from BeginFrameObserverMixIn instead, then you can
remove a bunch of the stuff below.

+ public:
+  DisplayScheduler(OutputSurface* output_surface,
+                   Display* display,
+                   scoped_refptr<base::SingleThreadTaskRunner> task_runner);
+  ~DisplayScheduler() override;
+
+  void DisplayDamaged();
+  void DidSwapBuffers();
+  void DidSwapBuffersComplete();
+  void CommitVSyncParameters(base::TimeTicks timebase,
+                             base::TimeDelta interval);
+  void OutputSurfaceLost();
+
+  // BeginFrameObserverImplementation.
+  void OnBeginFrame(const BeginFrameArgs& args) override;
+  const BeginFrameArgs LastUsedBeginFrameArgs() const override;
+  void AsValueInto(base::debug::TracedValue* dict) const override;
+
+ private:
+  void Draw();
+
+  OutputSurface* output_surface_;
+  Display* display_;
+  scoped_ptr<SyntheticBeginFrameSource> begin_frame_source_;

[mithro-old, 2015/03/11 04:19:25]

Why are we hard coding this to a SyntheticBFS rather than just using a generic
BFS?

+  scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
+
+  RollingTimeDeltaHistory draw_duration_history_;
+  BeginFrameArgs current_begin_frame_args_;
+
+  bool output_surface_lost_;
+  bool need_draw_;
+  int pending_frames_;
+
+  base::WeakPtrFactory<DisplayScheduler> weak_ptr_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(DisplayScheduler);
+};
+
+}  // namespace cc
+
+#endif  // CC_SURFACES_DISPLAY_SCHEDULER_H_