Fix more stuck frames with external frame control (again)

- disable sending of missed frames to frame observers added after we
cancel frame in ExternalBeginFrameSourceMojo to avoid sending multiple
frames, or sending frames at the time when the client does not intend.

- force full frames (i.e. animation_only = false) till we have a first
frame drawn. We used to do this on the client side, but this really
belongs to the back-end (and maybe further down to the renderer).

Bug: 1149042
Change-Id: Id1d79fbd4d6f355ebf6b9a441a5df772c7cf3b4a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2538488Reviewed-by: Sunny Sachanandani <sunnyps@chromium.org>
Commit-Queue: Andrey Kosyakov <caseq@chromium.org>
Cr-Commit-Position: refs/heads/master@{#829122}

components/viz/service/frame_sinks/external_begin_frame_source_mojo.cc

@@ -4,6 +4,8 @@
 
 #include "components/viz/service/frame_sinks/external_begin_frame_source_mojo.h"
 
+#include <utility>
+
 #include "components/viz/service/frame_sinks/frame_sink_manager_impl.h"
 
 namespace viz {
@@ -31,7 +33,12 @@ void ExternalBeginFrameSourceMojo::IssueExternalBeginFrame(
   DCHECK(!pending_frame_callback_) << "Got overlapping IssueExternalBeginFrame";
   original_source_id_ = args.frame_id.source_id;
 
-  OnBeginFrame(args);
+  BeginFrameArgs args_copy(args);
+  // Force full frame till we have first real draw.
+  if (!last_frame_acknowledged_)
+    args_copy.animate_only = false;
+  last_frame_acknowledged_ = false;
+  OnBeginFrame(args_copy);
 
   pending_frame_callback_ = std::move(callback);
 
@@ -89,11 +96,16 @@ void ExternalBeginFrameSourceMojo::MaybeProduceFrameCallback() {
   BeginFrameAck nak(last_begin_frame_args_.frame_id.source_id,
                     last_begin_frame_args_.frame_id.sequence_number,
                     /*has_damage=*/false);
+  // Prevent missing begin frames from being sent to sinks that came late,
+  // as this may result in two overlapping frames being sent, which is not
+  // supported with full pipeline mode.
+  last_begin_frame_args_ = BeginFrameArgs();
   std::move(pending_frame_callback_).Run(nak);
 }
 
 void ExternalBeginFrameSourceMojo::OnDisplayDidFinishFrame(
     const BeginFrameAck& ack) {
+  last_frame_acknowledged_ = true;
   if (!pending_frame_callback_)
     return;
   std::move(pending_frame_callback_).Run(ack);

components/viz/service/frame_sinks/external_begin_frame_source_mojo.h

@@ -82,6 +82,7 @@ class VIZ_SERVICE_EXPORT ExternalBeginFrameSourceMojo
   // IssueExternalBeginFrame. Note this is likely to be different from our
   // source id, but this is what will be reported to FrameSinkObserver methods.
   uint64_t original_source_id_ = BeginFrameArgs::kStartingSourceId;
+  bool last_frame_acknowledged_ = false;
 
   base::flat_set<FrameSinkId> pending_frame_sinks_;
   Display* display_ = nullptr;