viz: Fix presentation feedback frame token DCHECKs

Frame tokens are provided by the client and the only guarantee that's
enforced is that they're non-zero.  Therefore, we should not DCHECK
other invariants like not receiving two PresentationFeedbacks for the
same token.

Also add a deserialization error if the client sends a zero frame token
since we have DCHECKs for that anyway.

Bug: 958310
Change-Id: I4ffad483b46999c084f88ca62a0bb824522e6d37
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1594070Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: kylechar <kylechar@chromium.org>
Commit-Queue: Sunny Sachanandani <sunnyps@chromium.org>
Cr-Commit-Position: refs/heads/master@{#658802}

components/viz/service/frame_sinks/compositor_frame_sink_support.cc

@@ -566,7 +566,6 @@ void CompositorFrameSinkSupport::DidPresentCompositorFrame(
     uint32_t presentation_token,
     const gfx::PresentationFeedback& feedback) {
   DCHECK(presentation_token);
-  DCHECK(!presentation_feedbacks_.count(presentation_token));
   presentation_feedbacks_.emplace(presentation_token, feedback);
   UpdateNeedsBeginFramesInternal();
 }

services/viz/public/cpp/compositing/compositor_frame_metadata_struct_traits.cc

@@ -28,11 +28,14 @@ bool StructTraits<viz::mojom::CompositorFrameMetadataDataView,
   if (!data.ReadScrollableViewportSize(&out->scrollable_viewport_size))
     return false;
 
+  if (data.frame_token() == 0u)
+    return false;
+  out->frame_token = data.frame_token();
+
   out->may_contain_video = data.may_contain_video();
   out->is_resourceless_software_draw_with_scroll_or_animation =
       data.is_resourceless_software_draw_with_scroll_or_animation();
   out->content_source_id = data.content_source_id();
-  out->frame_token = data.frame_token();
   out->send_frame_token_to_embedder = data.send_frame_token_to_embedder();
   out->root_background_color = data.root_background_color();
   out->min_page_scale_factor = data.min_page_scale_factor();