Add a TODO to track HW overlay plane CSC.

This CL just adds a TODO in the overlay candidate code, where we
currently reject HW overlays candidates if they have a color
transform matrix, since we should be able to handle those
once crbug.com/792757 is addressed.


Bug: 792757
TBR: reveman
Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.android:android_optional_gpu_tests_rel
Change-Id: If0211c553d82dfca212d6e9b52e0ebfd5f861dd1
Reviewed-on: https://chromium-review.googlesource.com/813062
Commit-Queue: Daniele Castagna <dcastagna@chromium.org>
Reviewed-by: Ahmed Fakhry <afakhry@chromium.org>
Cr-Commit-Position: refs/heads/master@{#522356}

cc/output/overlay_candidate.cc

@@ -197,7 +197,9 @@ bool OverlayCandidate::FromDrawQuad(DisplayResourceProvider* resource_provider,
                                     const SkMatrix44& output_color_matrix,
                                     const viz::DrawQuad* quad,
                                     OverlayCandidate* candidate) {
-  // Overlays are not compatible with output color matrices.
+  // It is currently not possible to set a color conversion matrix on an HW
+  // overlay plane.
+  // TODO(dcastagna): Remove this check once crbug.com/792757 is resolved.
   if (!output_color_matrix.isIdentity())
     return false;