ui: Cleanup class/struct forward declarations

cc/layers/solid_color_layer_impl_unittest.cc

Index: cc/layers/solid_color_layer_impl_unittest.cc
diff --git a/cc/layers/solid_color_layer_impl_unittest.cc b/cc/layers/solid_color_layer_impl_unittest.cc
index dd30563580b280f7cb88991bcb3d3eec5f1cc008..312449b2d882b483b292db23460a479d2cbb463f 100644
--- a/cc/layers/solid_color_layer_impl_unittest.cc
+++ b/cc/layers/solid_color_layer_impl_unittest.cc
@@ -8,6 +8,7 @@
 
 #include <vector>
 
+#include "cc/animation/animation_host.h"
 #include "cc/layers/append_quads_data.h"
 #include "cc/layers/solid_color_layer.h"
 #include "cc/quads/solid_color_draw_quad.h"
@@ -135,8 +136,9 @@ TEST(SolidColorLayerImplTest, VerifyOpaqueRect) {
 
   FakeLayerTreeHostClient client;
   TestTaskGraphRunner task_graph_runner;
-  std::unique_ptr<FakeLayerTreeHost> host =
-      FakeLayerTreeHost::Create(&client, &task_graph_runner);
+  auto animation_host = AnimationHost::CreateForTesting(ThreadInstance::MAIN);
+  std::unique_ptr<FakeLayerTreeHost> host = FakeLayerTreeHost::Create(
+      &client, &task_graph_runner, animation_host.get());
   host->SetRootLayer(root);
 
   LayerTreeHostCommon::CalcDrawPropsMainInputsForTesting inputs(