exo::CompositorFrameSink uses CompositorFrameSinkHolder* instead of mojo interface pointer

components/exo/compositor_frame_sink.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_EXO_EXO_COMPOSITOR_FRAME_SINK_H_
 #define COMPONENTS_EXO_EXO_COMPOSITOR_FRAME_SINK_H_
 
 #include "cc/ipc/compositor_frame.mojom.h"
 #include "cc/ipc/mojo_compositor_frame_sink.mojom.h"
 #include "cc/resources/transferable_resource.h"
 #include "cc/surfaces/compositor_frame_sink_support.h"
 #include "cc/surfaces/compositor_frame_sink_support_client.h"
 #include "mojo/public/cpp/bindings/strong_binding.h"
 
 namespace exo {
 
+class CompositorFrameSinkHolder;
+
 class CompositorFrameSink : public cc::CompositorFrameSinkSupportClient,
                             public cc::mojom::MojoCompositorFrameSink {
  public:
   CompositorFrameSink(const cc::FrameSinkId& frame_sink_id,
                       cc::SurfaceManager* surface_manager,
-                      cc::mojom::MojoCompositorFrameSinkClientPtr client);
+                      CompositorFrameSinkHolder* client);
 
   ~CompositorFrameSink() override;
 
   // Overridden from cc::mojom::MojoCompositorFrameSink:
   void SetNeedsBeginFrame(bool needs_begin_frame) override;
   void SubmitCompositorFrame(const cc::LocalFrameId& local_frame_id,
                              cc::CompositorFrame frame) override;
   void AddSurfaceReferences(
       const std::vector<cc::SurfaceReference>& references) override;
   void RemoveSurfaceReferences(
       const std::vector<cc::SurfaceReference>& references) override;
   void EvictFrame() override;
   void Require(const cc::LocalFrameId& local_frame_id,
                const cc::SurfaceSequence& sequence) override;
   void Satisfy(const cc::SurfaceSequence& sequence) override;
 
   // Overridden from cc::CompositorFrameSinkSupportClient:
   void DidReceiveCompositorFrameAck() override;
   void OnBeginFrame(const cc::BeginFrameArgs& args) override;
   void ReclaimResources(const cc::ReturnedResourceArray& resources) override;
   void WillDrawSurface() override;
 
  private:
   cc::CompositorFrameSinkSupport support_;
-  cc::mojom::MojoCompositorFrameSinkClientPtr client_;
+  CompositorFrameSinkHolder* client_;
   cc::ReturnedResourceArray surface_returned_resources_;
   mojo::StrongBindingPtr<cc::mojom::MojoCompositorFrameSink> binding_;

[Fady Samuel, 2017/01/13 19:14:28]

Try restoring the existing code and making this binding_ the first member
variable. Make CompositorFrameSinkSupport the last member variable.

This would cause CompositorFrameSinkSupport to be destroyed first, and
mojo::StrongBindingPtr<cc::mojom::MojoCompositorFrameSink> to be destroyed last.
I'm curious what would happen.

 
   DISALLOW_COPY_AND_ASSIGN(CompositorFrameSink);
 };
 
 }  // namespace exo
 
 #endif  // COMPONENTS_EXO_EXO_COMPOSITOR_FRAME_SINK_H_