Add observers to FrameSinkManagerHost.

content/browser/renderer_host/offscreen_canvas_surface_impl.h

Index: content/browser/renderer_host/offscreen_canvas_surface_impl.h
diff --git a/content/browser/renderer_host/offscreen_canvas_surface_impl.h b/content/browser/renderer_host/offscreen_canvas_surface_impl.h
index 14d4b0a439c3e0eb71ccbde8e9133b5b36b00bae..827d9af84793a7c416c15abb003c68d4d5f6e3e3 100644
--- a/content/browser/renderer_host/offscreen_canvas_surface_impl.h
+++ b/content/browser/renderer_host/offscreen_canvas_surface_impl.h
@@ -5,27 +5,40 @@
 #ifndef CONTENT_BROWSER_RENDERER_HOST_OFFSCREEN_CANVAS_SURFACE_IMPL_H_
 #define CONTENT_BROWSER_RENDERER_HOST_OFFSCREEN_CANVAS_SURFACE_IMPL_H_
 
-#include "cc/surfaces/surface_id.h"
-#include "mojo/public/cpp/bindings/strong_binding.h"
+#include "cc/surfaces/frame_sink_id.h"
+#include "cc/surfaces/surface_info.h"
+#include "content/browser/compositor/frame_sink_observer.h"
+#include "content/common/content_export.h"
+#include "mojo/public/cpp/bindings/binding.h"
 #include "third_party/WebKit/public/platform/modules/offscreencanvas/offscreen_canvas_surface.mojom.h"
 
 namespace content {
 
+class OffscreenCanvasProviderImpl;
+
 // The browser owned object for an offscreen canvas connection. Holds
 // connections to both the renderer and frame sink manager.
 class CONTENT_EXPORT OffscreenCanvasSurfaceImpl
-    : public blink::mojom::OffscreenCanvasSurface {
+    : public blink::mojom::OffscreenCanvasSurface,

[Fady Samuel, 2017/04/28 04:58:00]

Maybe this thing is actually an "OffscreenCanvasEmbedder" then? That way we
avoid the term "Surface"? Note maybe we can rename things in a separate CL.

[kylechar, 2017/05/01 19:07:48]

OffscreenCanvasEmbedder works too.

+      public FrameSinkObserver {
  public:
   OffscreenCanvasSurfaceImpl(
       const cc::FrameSinkId& parent_frame_sink_id,
       const cc::FrameSinkId& frame_sink_id,
-      blink::mojom::OffscreenCanvasSurfaceClientPtr client);
+      OffscreenCanvasProviderImpl* provider,
+      blink::mojom::OffscreenCanvasSurfaceClientPtr client,
+      blink::mojom::OffscreenCanvasSurfaceRequest request);
   ~OffscreenCanvasSurfaceImpl() override;
 
-  static void Create(const cc::FrameSinkId& parent_frame_sink_id,
-                     const cc::FrameSinkId& frame_sink_id,
-                     blink::mojom::OffscreenCanvasSurfaceClientPtr client,
-                     blink::mojom::OffscreenCanvasSurfaceRequest request);
+  const cc::FrameSinkId& frame_sink_id() const { return frame_sink_id_; }
+
+  const cc::FrameSinkId& parent_frame_sink_id() const {
+    return parent_frame_sink_id_;
+  }
+
+  const cc::LocalSurfaceId& local_surface_id() const {
+    return local_surface_id_;
+  }
 
   // Creates a MojoCompositorFrameSink connection to FrameSinkManager for an
   // offscreen canvas client. The corresponding private interface will be owned
@@ -35,35 +48,31 @@ class CONTENT_EXPORT OffscreenCanvasSurfaceImpl
       cc::mojom::MojoCompositorFrameSinkClientPtr client,
       cc::mojom::MojoCompositorFrameSinkRequest request);
 
-  void OnSurfaceCreated(const cc::SurfaceInfo& surface_info);
-
   // blink::mojom::OffscreenCanvasSurface implementation.
   void Require(const cc::SurfaceId& surface_id,
                const cc::SurfaceSequence& sequence) override;
   void Satisfy(const cc::SurfaceSequence& sequence) override;
 
-  const cc::FrameSinkId& frame_sink_id() const { return frame_sink_id_; }
-
-  const cc::FrameSinkId& parent_frame_sink_id() const {
-    return parent_frame_sink_id_;
-  }
-
-  const cc::LocalSurfaceId& current_local_surface_id() const {
-    return current_local_surface_id_;
-  }
+  // FrameSinkObserver implementation.
+  void OnSurfaceCreated(const cc::SurfaceInfo& surface_info) override;
 
  private:
+  // Registered as a callback for when |binding_| is closed.
+  void OnSurfaceConnectionClosed();
+
   blink::mojom::OffscreenCanvasSurfaceClientPtr client_;
-  mojo::StrongBindingPtr<blink::mojom::OffscreenCanvasSurface> binding_;
+  mojo::Binding<blink::mojom::OffscreenCanvasSurface> binding_;
 
   // Private connection for the CompositorFrameSink. The CompositorFrameSink
   // will not be destroyed until both private and offscreen canvas client
   // connections are closed.
   cc::mojom::MojoCompositorFrameSinkPrivatePtr compositor_frame_sink_private_;
 
+  OffscreenCanvasProviderImpl* provider_;
+
   // Surface-related state
   const cc::FrameSinkId frame_sink_id_;
-  cc::LocalSurfaceId current_local_surface_id_;
+  cc::LocalSurfaceId local_surface_id_;
   const cc::FrameSinkId parent_frame_sink_id_;
 
   bool has_created_compositor_frame_sink_ = false;