cc: Make LayerTreeImpl tests stop subclassing LayerImplTest.

cc/test/layer_test_common.cc

Index: cc/test/layer_test_common.cc
diff --git a/cc/test/layer_test_common.cc b/cc/test/layer_test_common.cc
index b08f7444bbe3484f116b36488663c82638ced00a..bf7a0aa4df887218ac745c72041d4ed196e53355 100644
--- a/cc/test/layer_test_common.cc
+++ b/cc/test/layer_test_common.cc
@@ -128,7 +128,7 @@ LayerTestCommon::LayerImplTest::LayerImplTest(const LayerTreeSettings& settings)
   host_->host_impl()->active_tree()->SetRootLayerForTesting(std::move(root));
   root_layer_for_testing()->SetHasRenderSurface(true);
   host_->host_impl()->SetVisible(true);
-  host_->host_impl()->InitializeRenderer(output_surface_.get());
+  EXPECT_TRUE(host_->host_impl()->InitializeRenderer(output_surface_.get()));
 
   const int timeline_id = AnimationIdProvider::NextTimelineId();
   timeline_ = AnimationTimeline::Create(timeline_id);