Remove irrelevant comment in OffscreenCanvasResourceProvider

To avoid confusion

TBR=zakerinasab@chromium.org

Bug: None
Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
Change-Id: I9f1b5412790672b2792d004840bcca2fbf44c997
Reviewed-on: https://chromium-review.googlesource.com/1055753
Commit-Queue: Olivia Lai <xlai@chromium.org>
Reviewed-by: Olivia Lai <xlai@chromium.org>
Cr-Commit-Position: refs/heads/master@{#558002}

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

@@ -70,8 +70,6 @@ void OffscreenCanvasResourceProvider::TransferResource(
   resource->is_overlay_candidate = false;
 }
 
-// TODO(xlai): Handle error cases when, by any reason,
-// OffscreenCanvasResourceProvider fails to get image data.
 void OffscreenCanvasResourceProvider::SetTransferableResourceToSharedBitmap(
     viz::TransferableResource& resource,
     scoped_refptr<StaticBitmapImage> image) {