exo::CompositorFrameSinkHolder's release callbacks hold ref

components/exo/compositor_frame_sink_holder.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_COMPOSITOR_FRAME_SINK_HOLDER_H_
 #define COMPONENTS_EXO_COMPOSITOR_FRAME_SINK_HOLDER_H_
 
 #include <list>
 #include <map>
 #include <memory>
 
 #include "cc/ipc/mojo_compositor_frame_sink.mojom.h"
-#include "cc/resources/single_release_callback.h"
+#include "cc/resources/release_callback.h"
 #include "cc/resources/transferable_resource.h"
 #include "cc/scheduler/begin_frame_source.h"
 #include "components/exo/compositor_frame_sink.h"
 #include "components/exo/surface_observer.h"
 #include "mojo/public/cpp/bindings/binding.h"
 
 namespace exo {
 class Surface;
 
 // This class talks to MojoCompositorFrameSink and keeps track of references to
 // the contents of Buffers. It's keeped alive by references from
 // release_callbacks_. It's destroyed when its owning Surface is destroyed and
 // the last outstanding release callback is called.
 class CompositorFrameSinkHolder
     : public base::RefCounted<CompositorFrameSinkHolder>,
       public cc::ExternalBeginFrameSourceClient,
       public cc::mojom::MojoCompositorFrameSinkClient,
       public cc::BeginFrameObserver,
       public SurfaceObserver {
  public:
   CompositorFrameSinkHolder(
       Surface* surface,
       std::unique_ptr<CompositorFrameSink> frame_sink,
       cc::mojom::MojoCompositorFrameSinkClientRequest request);
 
   bool HasReleaseCallbackForResource(cc::ResourceId id);
-  void AddResourceReleaseCallback(
+  void SetResourceReleaseCallback(
       cc::ResourceId id,
-      std::unique_ptr<cc::SingleReleaseCallback> callback);
+      std::unique_ptr<cc::ReleaseCallback> callback);
 
   CompositorFrameSink* GetCompositorFrameSink() { return frame_sink_.get(); }
 
   base::WeakPtr<CompositorFrameSinkHolder> GetWeakPtr() {
     return weak_factory_.GetWeakPtr();
   }
 
   using FrameCallback = base::Callback<void(base::TimeTicks frame_time)>;
   void ActivateFrameCallbacks(std::list<FrameCallback>* frame_callbacks);
   void CancelFrameCallbacks();
@@ skipping 12 matching lines @@
   // Overridden from cc::BeginFrameObserver:
   const cc::BeginFrameArgs& LastUsedBeginFrameArgs() const override;
   void OnBeginFrameSourcePausedChanged(bool paused) override;
 
   // Overridden from cc::ExternalBeginFrameSouceClient:
   void OnNeedsBeginFrames(bool needs_begin_frames) override;
 
   // Overridden from SurfaceObserver:
   void OnSurfaceDestroying(Surface* surface) override;
 
+ protected:
+  ~CompositorFrameSinkHolder() override;
+
  private:
   friend class base::RefCounted<CompositorFrameSinkHolder>;
 
-  ~CompositorFrameSinkHolder() override;
-
   void UpdateNeedsBeginFrame();
 
-  // Each release callback holds a reference to the CompositorFrameSinkHolder
-  // itself to keep it alive. Running and erasing the callbacks might result in
-  // the instance being destroyed. Therefore, we should not access any member
-  // variables after running and erasing the callbacks.
+  // A collection of callbacks used to release resources.
   using ResourceReleaseCallbackMap =
-      std::map<int,
-               std::pair<scoped_refptr<CompositorFrameSinkHolder>,
-                         std::unique_ptr<cc::SingleReleaseCallback>>>;
+      std::map<int, std::unique_ptr<cc::ReleaseCallback>>;
   ResourceReleaseCallbackMap release_callbacks_;
 
   Surface* surface_;
   std::unique_ptr<CompositorFrameSink> frame_sink_;
 
   std::list<FrameCallback> active_frame_callbacks_;
   std::unique_ptr<cc::ExternalBeginFrameSource> begin_frame_source_;
   bool needs_begin_frame_ = false;
   cc::BeginFrameArgs last_begin_frame_args_;
   mojo::Binding<cc::mojom::MojoCompositorFrameSinkClient> binding_;
 
   base::WeakPtrFactory<CompositorFrameSinkHolder> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(CompositorFrameSinkHolder);
 };
 
 }  // namespace exo
 
 #endif  // COMPONENTS_EXO_COMPOSITOR_FRAME_SINK_HOLDER_H_