Implement service-side surface synchronization

cc/surfaces/surface.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_SURFACE_H_
 #define CC_SURFACES_SURFACE_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <map>
 #include <memory>
 #include <set>
 #include <unordered_set>
 #include <vector>
 
 #include "base/callback.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "base/optional.h"
 #include "cc/output/copy_output_request.h"
 #include "cc/surfaces/frame_sink_id.h"
+#include "cc/surfaces/pending_frame_observer.h"
 #include "cc/surfaces/surface_factory.h"
 #include "cc/surfaces/surface_id.h"
 #include "cc/surfaces/surface_sequence.h"
 #include "cc/surfaces/surfaces_export.h"
 #include "ui/gfx/geometry/size.h"
 
 namespace ui {
 class LatencyInfo;
 }
 
@@ skipping 14 matching lines @@
   const SurfaceId& surface_id() const { return surface_id_; }
   const SurfaceId& previous_frame_surface_id() const {
     return previous_frame_surface_id_;
   }
 
   void SetPreviousFrameSurface(Surface* surface);
 
   void QueueFrame(CompositorFrame frame, const DrawCallback& draw_callback);
   void EvictFrame();
   void RequestCopyOfOutput(std::unique_ptr<CopyOutputRequest> copy_request);
+
+  // Notifies the Surface that a blocking SurfaceId now has an active frame.
+  void NotifySurfaceIdAvailable(const SurfaceId& surface_id);
+
+  void AddObserver(PendingFrameObserver* observer);
+  void RemoveObserver(PendingFrameObserver* observer);
+
+  // Called if a deadline has been hit and this surface is not yet active but
+  // it's marked as respecting deadlines.
+  void ActivatePendingFrameForDeadline();
+
   // Adds each CopyOutputRequest in the current frame to copy_requests. The
   // caller takes ownership of them. |copy_requests| is keyed by RenderPass ids.
   void TakeCopyOutputRequests(
       std::multimap<int, std::unique_ptr<CopyOutputRequest>>* copy_requests);
 
   // Returns the most recent frame that is eligible to be rendered.
-  // You must check whether HasFrame() returns true before calling this method.
-  const CompositorFrame& GetEligibleFrame() const;
+  // You must check whether HasActiveFrame() returns true before calling this
+  // method.
+  const CompositorFrame& GetActiveFrame() const;
+
+  // Returns the currently pending frame. You must check where HasPendingFrame()
+  // returns true before calling this method.
+  const CompositorFrame& GetPendingFrame();
 
   // Returns a number that increments by 1 every time a new frame is enqueued.
   int frame_index() const { return frame_index_; }
 
   void TakeLatencyInfo(std::vector<ui::LatencyInfo>* latency_info);
   void RunDrawCallbacks();
 
   base::WeakPtr<SurfaceFactory> factory() { return factory_; }
 
   // Add a SurfaceSequence that must be satisfied before the Surface is
   // destroyed.
   void AddDestructionDependency(SurfaceSequence sequence);
 
   // Satisfy all destruction dependencies that are contained in sequences, and
   // remove them from sequences.
   void SatisfyDestructionDependencies(
       std::unordered_set<SurfaceSequence, SurfaceSequenceHash>* sequences,
       std::unordered_set<FrameSinkId, FrameSinkIdHash>* valid_id_namespaces);
   size_t GetDestructionDependencyCount() const {
     return destruction_dependencies_.size();
   }
 
   const std::vector<SurfaceId>& referenced_surfaces() const {
     return referenced_surfaces_;
   }
 
-  bool HasFrame() const { return current_frame_.has_value(); }
+  bool HasActiveFrame() const { return active_frame_.has_value(); }
+  bool HasPendingFrame() const { return pending_frame_.has_value(); }
 
   bool destroyed() const { return destroyed_; }
   void set_destroyed(bool destroyed) { destroyed_ = destroyed; }
 
  private:
+  void ActivatePendingFrame();

[kylechar, 2017/02/09 15:50:31]

What does ActivePendingFrame() do exactly? Can you leave a comment.

+  // Called when all of the surface's dependencies have been resolved.
+  void ActivateFrame(CompositorFrame frame);
+  void UpdateBlockingSurfaces(
+      const base::Optional<CompositorFrame>& previous_pending_frame,
+      const CompositorFrame& current_frame);
+
   void UnrefFrameResources(const CompositorFrame& frame_data);
   void ClearCopyRequests();
 
   SurfaceId surface_id_;
   SurfaceId previous_frame_surface_id_;
   base::WeakPtr<SurfaceFactory> factory_;
   // TODO(jamesr): Support multiple frames in flight.
-  base::Optional<CompositorFrame> current_frame_;
+  base::Optional<CompositorFrame> pending_frame_;
+  base::Optional<CompositorFrame> active_frame_;
   int frame_index_;
   bool destroyed_;
   std::vector<SurfaceSequence> destruction_dependencies_;
 
   // This surface may have multiple BeginFrameSources if it is
   // on multiple Displays.
   std::set<BeginFrameSource*> begin_frame_sources_;
 
   std::vector<SurfaceId> referenced_surfaces_;
 
+  SurfaceDependencies blocking_surfaces_;
+  base::ObserverList<PendingFrameObserver, true> observers_;
+
   DrawCallback draw_callback_;
 
   DISALLOW_COPY_AND_ASSIGN(Surface);
 };
 
+using PendingSurfaceSet = base::flat_set<Surface*>;
+
 }  // namespace cc
 
 #endif  // CC_SURFACES_SURFACE_H_