blink/canvas: Use front buffer textures for swap chain snapshots.

Use front buffer textures directly for snapshots with swap chain
resources instead of a copy via skia.

R=sunnyps@chromium.org

Bug: 962630
Change-Id: I88f6e5b098b060325cff06cd3a140d85146f60b4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1949663
Auto-Submit: Khushal <khushalsagar@chromium.org>
Reviewed-by: Sunny Sachanandani <sunnyps@chromium.org>
Commit-Queue: Khushal <khushalsagar@chromium.org>
Cr-Commit-Position: refs/heads/master@{#721372}

third_party/blink/renderer/platform/graphics/canvas_resource_provider.cc

@@ -553,7 +553,12 @@ class CanvasResourceProviderSwapChain final : public CanvasResourceProvider {
 
   scoped_refptr<StaticBitmapImage> Snapshot() override {
     TRACE_EVENT0("blink", "CanvasResourceProviderSwapChain::Snapshot");
-    return SnapshotInternal();
+
+    // Use ProduceCanvasResource to ensure any queued commands are flushed and
+    // the resource is updated.
+    if (auto resource = ProduceCanvasResource())
+      return resource->Bitmap();
+    return nullptr;
   }
 
   sk_sp<SkSurface> CreateSkSurface() const override {
@@ -1048,10 +1053,7 @@ scoped_refptr<StaticBitmapImage> CanvasResourceProvider::SnapshotInternal() {
     return nullptr;
 
   auto paint_image = MakeImageSnapshot();
-  if (paint_image.GetSkImage()->isTextureBacked() && ContextProviderWrapper()) {
-    return AcceleratedStaticBitmapImage::CreateFromSkImage(
-        paint_image.GetSkImage(), ContextProviderWrapper());
-  }
+  DCHECK(!paint_image.GetSkImage()->isTextureBacked());
   return UnacceleratedStaticBitmapImage::Create(std::move(paint_image));
 }