Create manager to track OffscreenCanvasSurfaceImpl instances

content/browser/renderer_host/offscreen_canvas_surface_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 CONTENT_BROWSER_RENDERER_HOST_OFFSCREEN_CANVAS_SURFACE_IMPL_H_
 #define CONTENT_BROWSER_RENDERER_HOST_OFFSCREEN_CANVAS_SURFACE_IMPL_H_
 
+#include "base/memory/weak_ptr.h"
 #include "cc/surfaces/surface_id.h"
 #include "cc/surfaces/surface_id_allocator.h"
 #include "mojo/public/cpp/bindings/interface_request.h"
 #include "mojo/public/cpp/bindings/string.h"
 #include "third_party/WebKit/public/platform/modules/offscreencanvas/offscreen_canvas_surface.mojom.h"
 
 namespace content {
 
 class OffscreenCanvasSurfaceImpl : public blink::mojom::OffscreenCanvasSurface {
  public:
   OffscreenCanvasSurfaceImpl();
   ~OffscreenCanvasSurfaceImpl() override;
 
   static void Create(blink::mojom::OffscreenCanvasSurfaceRequest request);
 
   // blink::mojom::OffscreenCanvasSurface implementation.
-  void GetSurfaceId(const GetSurfaceIdCallback& callback) override;
+  void GetSurfaceId(uint32_t canvas_id,
+                    const GetSurfaceIdCallback& callback) override;
   void Require(const cc::SurfaceId& surface_id,
                const cc::SurfaceSequence& sequence) override;
   void Satisfy(const cc::SurfaceSequence& sequence) override;
 
+  base::WeakPtr<OffscreenCanvasSurfaceImpl> GetWeakPtr() {
+    return weak_factory_.GetWeakPtr();
+  }
+
  private:
   // Surface-related state
   std::unique_ptr<cc::SurfaceIdAllocator> id_allocator_;
   cc::SurfaceId surface_id_;
 
+  // Each OffscreenCanvasSurfaceImpl instance takes care of one transferred
+  // HTMLCanvasElement with a unique canvas id.
+  int canvas_id_;

[dcheng, 2016/11/08 18:30:23]

Nit: ditto, make sure the types match please.

[xlai (Olivia), 2016/11/10 15:45:11]

Sure. I make all of them to be int32_t. I think we do have a case when canvas_id
is -1.

+
+  base::WeakPtrFactory<OffscreenCanvasSurfaceImpl> weak_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(OffscreenCanvasSurfaceImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_OFFSCREEN_CANVAS_SURFACE_IMPL_H_