Introduce DisplayCompositor Mojo API for Mus

components/mus/surfaces/compositor_frame_sink_impl.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 COMPONENTS_MUS_SURFACES_COMPOSITOR_FRAME_SINK_IMPL_H_
+#define COMPONENTS_MUS_SURFACES_COMPOSITOR_FRAME_SINK_IMPL_H_
+
+#include "base/memory/ref_counted.h"
+#include "cc/scheduler/begin_frame_source.h"
+#include "cc/surfaces/surface_factory.h"
+#include "cc/surfaces/surface_factory_client.h"
+#include "cc/surfaces/surface_id.h"
+#include "components/mus/public/interfaces/display_compositor.mojom.h"
+#include "components/mus/surfaces/surfaces_state.h"
+#include "mojo/public/cpp/bindings/strong_binding.h"
+
+namespace mus {
+
+class CompositorFrameSinkDelegate;
+
+// A client presents visuals to screen by submitting CompositorFrames to a

[rjkroege, 2016/05/19 22:08:38]

I think that the .mojom should be the repository of docs. And it would be nice
to have longer more helpful docs: e.g. base/callback.h lets one figure out how
to use the API.

[Fady Samuel, 2016/05/25 12:37:01]

Agreed, but I don't think we're ready for that yet. I'd like to iterate over
this API rapidly upstream first.

+// CompositorFrameSink.
+class CompositorFrameSinkImpl : public cc::SurfaceFactoryClient,
+                                public mojom::CompositorFrameSink,
+                                public cc::BeginFrameObserver {
+ public:
+  CompositorFrameSinkImpl(
+      CompositorFrameSinkDelegate* delegate,
+      int sink_id,
+      const scoped_refptr<SurfacesState>& surfaces_state,
+      mojo::InterfaceRequest<mojom::CompositorFrameSink> request,
+      mojom::CompositorFrameSinkClientPtr client);
+  ~CompositorFrameSinkImpl() override;
+
+  // mojom::CompositorFrameSink implementation.
+  void SetNeedsBeginFrame(bool needs_begin_frame) override;
+  void SubmitCompositorFrame(
+      mojom::CompositorFramePtr frame,
+      const SubmitCompositorFrameCallback& callback) override;

[rjkroege, 2016/05/19 22:08:38]

I want to know what happens when without reading lots or code. In particular:
there is a temporal relationship between callback's invocation and OnBeginFrame.
Sometimes. When and what is it?

[Fady Samuel, 2016/05/25 12:37:01]

I'm not sure if we've figured this out yet. Chrome has both. I need to figure
out if we actually need this callback anymore.

+
+ private:
+  // SurfaceFactoryClient implementation.
+  void ReturnResources(const cc::ReturnedResourceArray& resources) override;

[rjkroege, 2016/05/19 22:08:38]

why is this a SurfaceFactoryClient implementation?

isn't a CFS a Surface?

[Fady Samuel, 2016/05/25 12:37:01]

CompositorFrameSinkImpl is a SurfaceFactoryClient in order to send messages back
to the client via CompositorFrameSinkClient.

+  void WillDrawSurface(cc::SurfaceId surface_id,
+                       const gfx::Rect& damage_rect) override;
+  void SetBeginFrameSource(cc::BeginFrameSource* begin_frame_source) override;
+
+  // BeginFrameObserver implementation.
+  void OnBeginFrame(const cc::BeginFrameArgs& args) override;
+  const cc::BeginFrameArgs& LastUsedBeginFrameArgs() const override;
+  void OnBeginFrameSourcePausedChanged(bool paused) override;
+
+  void OnConnectionLost();
+
+  CompositorFrameSinkDelegate* const delegate_;
+  scoped_refptr<SurfacesState> surfaces_state_;
+  const int sink_id_;
+  cc::BeginFrameSource* begin_frame_source_;
+  bool needs_begin_frame_;
+  cc::BeginFrameArgs last_used_begin_frame_args_;
+  cc::SurfaceFactory factory_;
+  cc::SurfaceId surface_id_;
+  gfx::Size last_submitted_frame_size_;
+  mojom::CompositorFrameSinkClientPtr client_;
+  mojo::Binding<mojom::CompositorFrameSink> binding_;
+
+  DISALLOW_COPY_AND_ASSIGN(CompositorFrameSinkImpl);
+};
+
+}  // namespace mus
+
+#endif  // COMPONENTS_MUS_SURFACES_COMPOSITOR_FRAME_SINK_IMPL_H_