Make cc/paint have concrete types

third_party/WebKit/Source/platform/graphics/gpu/AcceleratedImageBufferSurface.h

Index: third_party/WebKit/Source/platform/graphics/gpu/AcceleratedImageBufferSurface.h
diff --git a/third_party/WebKit/Source/platform/graphics/gpu/AcceleratedImageBufferSurface.h b/third_party/WebKit/Source/platform/graphics/gpu/AcceleratedImageBufferSurface.h
index 7f388670a7de290478dcebe44b219cdd080bb643..ab8d1f6e23eda1858939e4e5485685ea1999820d 100644
--- a/third_party/WebKit/Source/platform/graphics/gpu/AcceleratedImageBufferSurface.h
+++ b/third_party/WebKit/Source/platform/graphics/gpu/AcceleratedImageBufferSurface.h
@@ -53,9 +53,7 @@ class PLATFORM_EXPORT AcceleratedImageBufferSurface
                                 SkColorType = kN32_SkColorType);
   ~AcceleratedImageBufferSurface() override {}
 
-  PaintCanvas* canvas() override {
-    return m_surface ? m_surface->getCanvas() : nullptr;
-  }
+  PaintCanvas* canvas() override { return m_canvas.get(); }
   bool isValid() const override;
   bool isAccelerated() const override { return true; }
   sk_sp<SkImage> newImageSnapshot(AccelerationHint, SnapshotReason) override;
@@ -63,7 +61,8 @@ class PLATFORM_EXPORT AcceleratedImageBufferSurface
 
  private:
   unsigned m_contextId;
-  sk_sp<PaintSurface> m_surface;  // Uses m_contextProvider.
+  sk_sp<SkSurface> m_surface;  // Uses m_contextProvider.
+  std::unique_ptr<PaintCanvas> m_canvas;
 };
 
 }  // namespace blink