Revert "Change call-sites now that SkCanvas is not ref-counted"

content/renderer/pepper/ppb_image_data_impl.h

Index: content/renderer/pepper/ppb_image_data_impl.h
diff --git a/content/renderer/pepper/ppb_image_data_impl.h b/content/renderer/pepper/ppb_image_data_impl.h
index 81c9a5a68ebd4631b9c854628a7baf7689392467..28fa33bd89f50b72252b1a6b26da5253c62698f2 100644
--- a/content/renderer/pepper/ppb_image_data_impl.h
+++ b/content/renderer/pepper/ppb_image_data_impl.h
@@ -149,7 +149,7 @@ class ImageDataPlatformBackend : public PPB_ImageData_Impl::Backend {
   std::unique_ptr<TransportDIB> dib_;
 
   // When the device is mapped, this is the image. Null when umapped.
-  std::unique_ptr<SkCanvas> mapped_canvas_;
+  sk_sp<SkCanvas> mapped_canvas_;
 
   DISALLOW_COPY_AND_ASSIGN(ImageDataPlatformBackend);
 };
@@ -179,7 +179,7 @@ class ImageDataSimpleBackend : public PPB_ImageData_Impl::Backend {
   std::unique_ptr<base::SharedMemory> shared_memory_;
   // skia_bitmap_ is backed by shared_memory_.
   SkBitmap skia_bitmap_;
-  std::unique_ptr<SkCanvas> skia_canvas_;
+  sk_sp<SkCanvas> skia_canvas_;
   uint32_t map_count_;
 
   DISALLOW_COPY_AND_ASSIGN(ImageDataSimpleBackend);