ui: Cleanup class/struct forward declarations

blimp/client/support/compositor/blimp_embedder_compositor.cc

Index: blimp/client/support/compositor/blimp_embedder_compositor.cc
diff --git a/blimp/client/support/compositor/blimp_embedder_compositor.cc b/blimp/client/support/compositor/blimp_embedder_compositor.cc
index 31c3931f0b7b38d700362a4d7f07deedd1240e5f..28317435bdb6d9f879249278ba3877abd0822e8b 100644
--- a/blimp/client/support/compositor/blimp_embedder_compositor.cc
+++ b/blimp/client/support/compositor/blimp_embedder_compositor.cc
@@ -115,13 +115,15 @@ BlimpEmbedderCompositor::BlimpEmbedderCompositor(
   compositor_dependencies_->GetSurfaceManager()->RegisterFrameSinkId(
       frame_sink_id_);
 
+  animation_host_ = cc::AnimationHost::CreateMainInstance();
+
   cc::LayerTreeHostInProcess::InitParams params;
   params.client = this;
   params.task_graph_runner = g_task_graph_runner.Pointer();
   cc::LayerTreeSettings settings;
   params.settings = &settings;
   params.main_task_runner = base::ThreadTaskRunnerHandle::Get();
-  params.animation_host = cc::AnimationHost::CreateMainInstance();
+  params.mutator_host = animation_host_.get();
   host_ = cc::LayerTreeHostInProcess::CreateSingleThreaded(this, &params);
 
   root_layer_->SetBackgroundColor(SK_ColorWHITE);