Finish offscreen canvas using FrameSinkMangerHost.

content/browser/renderer_host/offscreen_canvas_provider_impl.h

Index: content/browser/renderer_host/offscreen_canvas_provider_impl.h
diff --git a/content/browser/renderer_host/offscreen_canvas_provider_impl.h b/content/browser/renderer_host/offscreen_canvas_provider_impl.h
index 554e121a39a7b453d9d4a82aaf9ee8a8e05f1ea8..54f5070327302f00b36d329fced79d8f4c5a0626 100644
--- a/content/browser/renderer_host/offscreen_canvas_provider_impl.h
+++ b/content/browser/renderer_host/offscreen_canvas_provider_impl.h
@@ -5,14 +5,20 @@
 #ifndef CONTENT_BROWSER_RENDERER_HOST_OFFSCREEN_CANVAS_PROVIDER_IMPL_H_
 #define CONTENT_BROWSER_RENDERER_HOST_OFFSCREEN_CANVAS_PROVIDER_IMPL_H_
 
+#include <memory>
+
+#include "base/containers/flat_map.h"
 #include "cc/surfaces/frame_sink_id.h"
+#include "content/common/content_export.h"
 #include "mojo/public/cpp/bindings/binding_set.h"
 #include "third_party/WebKit/public/platform/modules/offscreencanvas/offscreen_canvas_surface.mojom.h"
 
 namespace content {
 
+class OffscreenCanvasSurfaceImpl;
+
 // Creates OffscreenCanvasSurfaces and MojoCompositorFrameSinks for a renderer.
-class OffscreenCanvasProviderImpl
+class CONTENT_EXPORT OffscreenCanvasProviderImpl
     : public blink::mojom::OffscreenCanvasProvider {
  public:
   explicit OffscreenCanvasProviderImpl(uint32_t renderer_client_id);
@@ -32,11 +38,20 @@ class OffscreenCanvasProviderImpl
       cc::mojom::MojoCompositorFrameSinkRequest request) override;
 
  private:
+  friend class OffscreenCanvasProviderImplTest;
+
+  // Destroys the |canvas_map_| entry for |frame_sink_id|. Provided as a
+  // callback to each OffscreenCanvasSurfaceImpl so they can destroy themselves.
+  void DestroyOffscreenCanvasSurface(cc::FrameSinkId frame_sink_id);
+
   // FrameSinkIds for offscreen canvas must use the renderer client id.
   const uint32_t renderer_client_id_;
 
   mojo::BindingSet<blink::mojom::OffscreenCanvasProvider> bindings_;
 
+  base::flat_map<cc::FrameSinkId, std::unique_ptr<OffscreenCanvasSurfaceImpl>>
+      canvas_map_;
+
   DISALLOW_COPY_AND_ASSIGN(OffscreenCanvasProviderImpl);
 };