cc/blimp: Add synchronization for scroll/scale state.

blimp/client/core/compositor/blimp_compositor.h

 // Copyright 2015 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 BLIMP_CLIENT_CORE_COMPOSITOR_BLIMP_COMPOSITOR_H_
 #define BLIMP_CLIENT_CORE_COMPOSITOR_BLIMP_COMPOSITOR_H_
 
 #include <memory>
 #include <vector>
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/threading/thread_checker.h"
 #include "blimp/client/core/compositor/blimp_compositor_frame_sink_proxy.h"
 #include "blimp/client/public/compositor/compositor_dependencies.h"
-#include "cc/blimp/compositor_state_deserializer_client.h"
+#include "cc/blimp/compositor_state_deserializer.h"
 #include "cc/surfaces/surface_factory_client.h"
 #include "cc/trees/layer_tree_host.h"
 #include "cc/trees/layer_tree_host_client.h"
 #include "cc/trees/layer_tree_settings.h"
 #include "cc/trees/remote_proto_channel.h"
 #include "ui/gfx/geometry/size.h"
 #include "ui/gfx/native_widget_types.h"
 
 namespace base {
 class SingleThreadTaskRunner;
 class Thread;
 }  // namespace base
 
 namespace cc {
 class InputHandler;
 
 namespace proto {
 class CompositorMessage;
 }  // namespace proto
 
-class CompositorStateDeserializer;
 class ContextProvider;
 class Layer;
 class LayerTreeHost;
 class LayerTreeSettings;
 class LocalFrameid;
 class Surface;
 class SurfaceFactory;
 class SurfaceIdAllocator;
 }  // namespace cc
 
@@ skipping 65 matching lines @@
   // LayerTreeHostClient implementation.
   void WillBeginMainFrame() override {}
   void DidBeginMainFrame() override {}
   void BeginMainFrame(const cc::BeginFrameArgs& args) override {}
   void BeginMainFrameNotExpectedSoon() override {}
   void UpdateLayerTreeHost() override;
   void ApplyViewportDeltas(const gfx::Vector2dF& inner_delta,
                            const gfx::Vector2dF& outer_delta,
                            const gfx::Vector2dF& elastic_overscroll_delta,
                            float page_scale,
-                           float top_controls_delta) override {}
+                           float top_controls_delta) override;
   void RequestNewCompositorFrameSink() override;
   void DidInitializeCompositorFrameSink() override;
   // TODO(khushalsagar): Need to handle context initialization failures.
   void DidFailToInitializeCompositorFrameSink() override {}
   void WillCommit() override {}
   void DidCommit() override {}
   void DidCommitAndDrawFrame() override;
   void DidReceiveCompositorFrameAck() override {}
   void DidCompletePageScaleAnimation() override {}
 
   // RemoteProtoChannel implementation.
   void SetProtoReceiver(ProtoReceiver* receiver) override;
   void SendCompositorProto(const cc::proto::CompositorMessage& proto) override;
 
   // BlimpCompositorFrameSinkProxy implementation.
   void BindToProxyClient(
       base::WeakPtr<BlimpCompositorFrameSinkProxyClient> proxy_client) override;
   void SubmitCompositorFrame(cc::CompositorFrame frame) override;
   void UnbindProxyClient() override;
 
   // SurfaceFactoryClient implementation.
   void ReturnResources(const cc::ReturnedResourceArray& resources) override;
   void SetBeginFrameSource(cc::BeginFrameSource* begin_frame_source) override {}
 
   // CompositorStateDeserializerClient implementation.
-  bool ShouldRetainClientScroll(int engine_layer_id,
-                                const gfx::ScrollOffset& new_offset) override;
-  bool ShouldRetainClientPageScale(float new_page_scale) override;
+  void DidUpdateLocalState() override;
 
   void HandleCompositorMessageToImpl(
       std::unique_ptr<cc::proto::CompositorMessage> message);
 
   // Called when the a ContextProvider has been created by the
   // CompositorDependencies class.  If |host_| is waiting on an
   // CompositorFrameSink this will build one for it.
   void OnContextProvidersCreated(
       const scoped_refptr<cc::ContextProvider>& compositor_context_provider,
       const scoped_refptr<cc::ContextProvider>& worker_context_provider);
@@ skipping 16 matching lines @@
 
   // Updates |pending_commit_trackers_|, decrementing the count and, if 0,
   // notifying the callback.  If |flush| is true, flushes all entries regardless
   // of the count.
   void CheckPendingCommitCounts(bool flush);
 
   // Acks a submitted CompositorFrame when it has been processed and another
   // frame should be started.
   void SubmitCompositorFrameAck();
 
-  // Called when the local copy of the layer with |engine_layer_id| on the
-  // engine was scrolled on the compositor thread.
-  void LayerScrolled(int engine_layer_id);
+  // Sends an update to the engine if the state on the client was modified and
+  // an ack for a previous update sent is not pending.
+  void SendClientStateUpdateIfPossible();
 
   // Set to true if we are using a LayerTreeHostInProcess to process frame
   // updates from the engine.
   const bool use_threaded_layer_tree_host_;
 
   BlimpCompositorClient* client_;
 
   BlimpCompositorDependencies* compositor_dependencies_;
 
   cc::FrameSinkId frame_sink_id_;
@@ skipping 37 matching lines @@
   // Stores a frame update received from the engine, when a threaded
   // LayerTreeHost is used. There can only be a single frame in flight at any
   // point.
   std::unique_ptr<cc::proto::CompositorMessage> pending_frame_update_;
 
   // Used with a threaded LayerTreeHost to deserialize proto updates from the
   // engine into the LayerTree.
   std::unique_ptr<cc::CompositorStateDeserializer>
       compositor_state_deserializer_;
 
+  // Set to true if the compositor state on the client was modified on the impl
+  // thread and an update needs to be sent to the engine.
+  bool client_state_modified_ = false;

[aelias_OOO_until_Jul13, 2016/10/26 04:04:12]

"dirty" is the jargon for this, so I suggest "client_state_dirty_"

[Khushal, 2016/10/26 19:02:35]

Done.

+
+  // Set to true if a client state update was sent to the engine and an ack for
+  // this update from the engine is pending.
+  bool client_state_update_ack_pending_ = false;
+
   base::WeakPtrFactory<BlimpCompositor> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(BlimpCompositor);
 };
 
 }  // namespace client
 }  // namespace blimp
 
 #endif  // BLIMP_CLIENT_CORE_COMPOSITOR_BLIMP_COMPOSITOR_H_