GetLatestInFlightSurface should output something for non-existent fallbacks

GetLatestInFlightSurface should not return nullptr if fallback doesn't exist.
Instead it should try to search for active surfaces in primary's FrameSinkId.

Bug: 875381
Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel
Change-Id: I8940c374b7f52f728e4d88c88358aeb177dc8520
Reviewed-on: https://chromium-review.googlesource.com/1179989Reviewed-by: Fady Samuel <fsamuel@chromium.org>
Commit-Queue: Andre Kaba <akaba@google.com>
Cr-Commit-Position: refs/heads/master@{#585139}

components/viz/service/display/surface_aggregator_unittest.cc

@@ -1606,7 +1606,7 @@ TEST_F(SurfaceAggregatorValidSurfaceTest, InvalidSurfaceReference) {
 // SolidColorDrawQuad should be placed in lieu of a frame.
 TEST_F(SurfaceAggregatorValidSurfaceTest, ValidSurfaceReferenceWithNoFrame) {
   LocalSurfaceId empty_local_surface_id = allocator_.GenerateId();
-  SurfaceId surface_with_no_frame_id(support_->frame_sink_id(),
+  SurfaceId surface_with_no_frame_id(kArbitraryFrameSinkId1,
                                      empty_local_surface_id);
 
   Quad quads[] = {

components/viz/service/frame_sinks/surface_synchronization_unittest.cc

@@ -2243,8 +2243,9 @@ TEST_F(SurfaceSynchronizationTest, LatestInFlightSurfaceWithoutFallback) {
   EXPECT_EQ(GetSurfaceForId(child_id1),
             GetLatestInFlightSurface(child_id2, child_id1));
 
-  // Fallback is not specified and primary doesn't exists so we return nullptr.
-  EXPECT_EQ(nullptr, GetLatestInFlightSurface(child_id2, base::nullopt));
+  // Fallback is not specified and |child_id1| is the latest.
+  EXPECT_EQ(GetSurfaceForId(child_id1),
+            GetLatestInFlightSurface(child_id2, base::nullopt));
 
   // Activate |child_id2|
   child_support1().SubmitCompositorFrame(child_id2.local_surface_id(),

components/viz/service/surfaces/surface_manager.cc

@@ -495,18 +495,11 @@ void SurfaceManager::RemoveTemporaryReference(const SurfaceId& surface_id,
 
 Surface* SurfaceManager::GetLatestInFlightSurface(
     const SurfaceRange& surface_range) {
-
   // If primary exists, we return it.
   Surface* primary_surface = GetSurfaceForId(surface_range.end());
   if (primary_surface && primary_surface->HasActiveFrame())
     return primary_surface;
 
-  // If fallback is not specified we return nullptr.
-  // TODO(akaba): after fixing https://crbug.com/861769 we need to return
-  // something older than primary.
-  if (!surface_range.start())
-    return nullptr;
-
   // If both end of the range exists, we try the primary's FrameSinkId first.
   Surface* latest_surface = GetLatestInFlightSurfaceForFrameSinkId(
       surface_range, surface_range.end().frame_sink_id());
@@ -519,9 +512,12 @@ Surface* SurfaceManager::GetLatestInFlightSurface(
 
   // Fallback might have neither temporary or presistent references, so we
   // consider it separately.
-  if (!latest_surface)
+  if (!latest_surface && surface_range.start())
     latest_surface = GetSurfaceForId(*surface_range.start());
+
+  if (latest_surface && latest_surface->HasActiveFrame())
     return latest_surface;
+  return nullptr;
 }
 
 void SurfaceManager::ExpireOldTemporaryReferences() {