Enforce valid LocalSurfaceId in LayerTreeImpl if Surface Sync is on

With surface sync on, the active tree is always expected to have a valid LocalSurfaceId, otherwise
surface invariants violations might be caused.

Bug: 672962
Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.android:android_optional_gpu_tests_rel
Change-Id: I71dea254f4208c76189dacfb4c4682aa6a5d72cb
Reviewed-on: https://chromium-review.googlesource.com/960585Reviewed-by: Fady Samuel <fsamuel@chromium.org>
Commit-Queue: Saman Sami <samans@chromium.org>
Cr-Commit-Position: refs/heads/master@{#542934}

cc/trees/layer_tree_host_impl.cc

@@ -1962,8 +1962,14 @@ bool LayerTreeHostImpl::DrawLayers(FrameData* frame) {
   compositor_frame.render_pass_list = std::move(frame->render_passes);
   // TODO(fsamuel): Once all clients get their viz::LocalSurfaceId from their
   // parent, the viz::LocalSurfaceId should hang off CompositorFrameMetadata.
-  if (settings_.enable_surface_synchronization &&
-      active_tree()->local_surface_id().is_valid()) {
+  if (settings_.enable_surface_synchronization) {
+    // If surface synchronization is on, we should always have a valid
+    // LocalSurfaceId in LayerTreeImpl unless we don't have a scheduler because
+    // without a scheduler commits are not deferred and LayerTrees without valid
+    // LocalSurfaceId might slip through, but single-thread-without-scheduler
+    // mode is only used in tests so it doesn't matter.
+    CHECK(!settings_.single_thread_proxy_scheduler ||
+          active_tree()->local_surface_id().is_valid());
     layer_tree_frame_sink_->SetLocalSurfaceId(
         active_tree()->local_surface_id());
     last_draw_local_surface_id_ = active_tree()->local_surface_id();

cc/trees/layer_tree_host_impl_unittest.cc

@@ -177,7 +177,11 @@ class LayerTreeHostImplTest : public testing::Test,
     animation_task_ = task;
     requested_animation_delay_ = delay;
   }
-  void DidActivateSyncTree() override {}
+  void DidActivateSyncTree() override {
+    // Make sure the active tree always has a valid LocalSurfaceId.
+    host_impl_->active_tree()->set_local_surface_id(
+        viz::LocalSurfaceId(1, base::UnguessableToken::Deserialize(2u, 3u)));
+  }
   void WillPrepareTiles() override {}
   void DidPrepareTiles() override {}
   void DidCompletePageScaleAnimationOnImplThread() override {
@@ -237,6 +241,8 @@ class LayerTreeHostImplTest : public testing::Test,
     bool init = host_impl_->InitializeRenderer(layer_tree_frame_sink_.get());
     host_impl_->SetViewportSize(gfx::Size(10, 10));
     host_impl_->active_tree()->PushPageScaleFromMainThread(1.f, 1.f, 1.f);
+    host_impl_->active_tree()->set_local_surface_id(
+        viz::LocalSurfaceId(1, base::UnguessableToken::Deserialize(2u, 3u)));
     // Set the viz::BeginFrameArgs so that methods which use it are able to.
     host_impl_->WillBeginImplFrame(viz::CreateBeginFrameArgsForTesting(
         BEGINFRAME_FROM_HERE, 0, 1,
@@ -3496,6 +3502,8 @@ class LayerTreeHostImplTestScrollbarAnimation : public LayerTreeHostImplTest {
     host_impl_->active_tree()->BuildPropertyTreesForTesting();
     host_impl_->active_tree()->DidBecomeActive();
     host_impl_->active_tree()->HandleScrollbarShowRequestsFromMain();
+    host_impl_->active_tree()->set_local_surface_id(
+        viz::LocalSurfaceId(1, base::UnguessableToken::Deserialize(2u, 3u)));
     DrawFrame();
 
     // SetScrollElementId will initialize the scrollbar which will cause it to
@@ -8796,7 +8804,10 @@ class LayerTreeHostImplViewportCoveredTest : public LayerTreeHostImplTest {
     VerifyLayerIsLargerThanViewport(last_on_draw_render_passes_);
   }
 
-  void DidActivateSyncTree() override { did_activate_pending_tree_ = true; }
+  void DidActivateSyncTree() override {
+    LayerTreeHostImplTest::DidActivateSyncTree();
+    did_activate_pending_tree_ = true;
+  }
 
   void set_gutter_quad_material(viz::DrawQuad::Material material) {
     gutter_quad_material_ = material;
@@ -8979,6 +8990,8 @@ TEST_F(LayerTreeHostImplTest, PartialSwapReceivesDamageRect) {
   root->test_properties()->AddChild(std::move(child));
   layer_tree_host_impl->active_tree()->SetRootLayerForTesting(std::move(root));
   layer_tree_host_impl->active_tree()->BuildPropertyTreesForTesting();
+  layer_tree_host_impl->active_tree()->set_local_surface_id(
+      viz::LocalSurfaceId(1, base::UnguessableToken::Deserialize(2u, 3u)));
 
   TestFrameData frame;