[cc] CompositorFrameSinkSupport: Defer BeginFrameAck of pending frames.

cc/surfaces/compositor_frame_sink_support.h

 // Copyright 2016 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_COMPOSITOR_FRAME_SINK_SUPPORT_H_
 #define CC_SURFACES_COMPOSITOR_FRAME_SINK_SUPPORT_H_
 
 #include <memory>
 #include <unordered_set>
 #include <vector>
 
 #include "base/compiler_specific.h"
 #include "base/memory/weak_ptr.h"
+#include "base/optional.h"
 #include "cc/output/compositor_frame.h"
 #include "cc/scheduler/begin_frame_source.h"
 #include "cc/surfaces/referenced_surface_tracker.h"
 #include "cc/surfaces/surface_factory.h"
 #include "cc/surfaces/surface_factory_client.h"
 #include "cc/surfaces/surface_id.h"
 #include "cc/surfaces/surfaces_export.h"
 
 namespace cc {
 
@@ skipping 25 matching lines @@
 
   void EvictFrame();
   void SetNeedsBeginFrame(bool needs_begin_frame);
   void BeginFrameDidNotSwap(const BeginFrameAck& ack);
   void SubmitCompositorFrame(const LocalSurfaceId& local_surface_id,
                              CompositorFrame frame);
   void RequestCopyOfSurface(std::unique_ptr<CopyOutputRequest> request);
   void ForceReclaimResources();
   void ClaimTemporaryReference(const SurfaceId& surface_id);
 
+  base::Optional<BeginFrameAck> begin_frame_ack_for_pending_frame_for_testing()
+      const {
+    return begin_frame_ack_for_pending_frame_;
+  }
+
  private:
   // Update surface references with SurfaceManager for current CompositorFrame
   // that has |local_surface_id|. UpdateReferences() must be called on
   // |reference_tracker_| before calling this. Will add and remove top-level
   // root references if |display_| is not null.
   void UpdateSurfaceReferences(const SurfaceId& last_surface_id,
                                const LocalSurfaceId& local_surface_id);
 
   void AddTopLevelRootReference(const SurfaceId& surface_id);
   void RemoveTopLevelRootReference(const SurfaceId& surface_id);
 
   void DidReceiveCompositorFrameAck();
+  void PendingFrameDiscarded();
 
   // SurfaceFactoryClient implementation.
   void ReferencedSurfacesChanged(
       const LocalSurfaceId& local_surface_id,
       const std::vector<SurfaceId>* active_referenced_surfaces,
       const std::vector<SurfaceId>* pending_referenced_surfaces) override;
   void ReturnResources(const ReturnedResourceArray& resources) override;
   void SetBeginFrameSource(BeginFrameSource* begin_frame_source) override;
   void WillDrawSurface(const LocalSurfaceId& local_surface_id,
                        const gfx::Rect& damage_rect) override;
+  void PendingFrameActivated(const LocalSurfaceId& local_surface_id) override;
+  void SurfaceDiscarded(const LocalSurfaceId& local_surface_id) override;
 
   // BeginFrameObserver implementation.
   void OnBeginFrame(const BeginFrameArgs& args) override;
   const BeginFrameArgs& LastUsedBeginFrameArgs() const override;
   void OnBeginFrameSourcePausedChanged(bool paused) override;
 
   void UpdateNeedsBeginFramesInternal();
+  // Send |ack| to BeginFrameSource and update
+  // |latest_confirmed_begin_frame_sequence_number_ / source_id_|.
+  void AcknowledgeBeginFrame(const BeginFrameAck& ack);
+  // Send a no-damage BeginFrameAck for the last BeginFrame that re-confirms the
+  // |latest_confirmed_begin_frame_sequence_number_|. Used to confirm past
+  // BeginFrames while a pending CompositorFrame is queued but not activated.
+  void AcknowledgeLastBeginFrameWithoutUpdates();
 
   CompositorFrameSinkSupportClient* const client_;
 
   SurfaceManager* const surface_manager_;
 
   const FrameSinkId frame_sink_id_;
 
   SurfaceFactory surface_factory_;
   // Counts the number of CompositorFrames that have been submitted and have not
   // yet received an ACK.
   int ack_pending_count_ = 0;
   ReturnedResourceArray surface_returned_resources_;
 
   // The begin frame source being observered. Null if none.
   BeginFrameSource* begin_frame_source_ = nullptr;
 
   // The last begin frame args generated by the begin frame source.
   BeginFrameArgs last_begin_frame_args_;
 
+  // The BeginFrameAck that will be issued when the last submitted
+  // CompositorFrame is activated. Only set if we recently submitted a
+  // CompositorFrame that has not been activated yet.
+  base::Optional<BeginFrameAck> begin_frame_ack_for_pending_frame_;
+  // The surface that the last CompositorFrame was submitted to. Used to
+  // determine whether the last CompositorFrame may have been dropped during
+  // SurfaceDiscarded.
+  LocalSurfaceId surface_id_for_pending_frame_;
+
+  // Whether the last BeginFrame was forwarded to the client.
+  bool last_begin_frame_sent_to_client_ = true;
+
+  uint32_t latest_confirmed_begin_frame_source_id_ = 0;
+  uint64_t latest_confirmed_begin_frame_sequence_number_ =
+      BeginFrameArgs::kInvalidFrameNumber;
+
   // Whether a request for begin frames has been issued.
-  bool needs_begin_frame_ = false;
+  bool client_needs_begin_frame_ = false;
 
   // Whether or not a frame observer has been added.
   bool added_frame_observer_ = false;
 
   // Track the surface references for the surface corresponding to this
   // compositor frame sink.
   ReferencedSurfaceTracker reference_tracker_;
 
   const bool is_root_;
 
@@ skipping 10 matching lines @@
   const bool handles_frame_sink_id_invalidation_;
 
   base::WeakPtrFactory<CompositorFrameSinkSupport> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(CompositorFrameSinkSupport);
 };
 
 }  // namespace cc
 
 #endif  // CC_SURFACES_COMPOSITOR_FRAME_SINK_SUPPORT_H_