cc: Cleanup class/struct forward declarations

cc/test/layer_tree_test.h

Index: cc/test/layer_tree_test.h
diff --git a/cc/test/layer_tree_test.h b/cc/test/layer_tree_test.h
index 63b3d597beea11feb995d541320d820fb5fca63a..f2a56c10b8c1c1fa2d3c00275568b0b58bcfae35 100644
--- a/cc/test/layer_tree_test.h
+++ b/cc/test/layer_tree_test.h
@@ -20,20 +20,14 @@ namespace cc {
 
 class AnimationHost;
 class AnimationPlayer;
-class FakeLayerTreeHostClient;
 class LayerImpl;
 class LayerTreeHost;
 class LayerTreeHostForTesting;
-class LayerTreeHostClient;
-class LayerTreeHostImpl;
 class LayerTreeTestCompositorFrameSinkClient;
 class Proxy;
-class ProxyImpl;
-class ProxyMain;
 class TestContextProvider;
 class TestCompositorFrameSink;
 class TestTaskGraphRunner;
-class TestWebGraphicsContext3D;
 
 // Creates the virtual viewport layer hierarchy under the given root_layer.
 // Convenient overload of the method below that creates a scrolling layer as
@@ -52,9 +46,7 @@ void CreateVirtualViewportLayers(Layer* root_layer,
                                  const gfx::Size& scroll_bounds,
                                  LayerTreeHost* host);
 
-class BeginTask;
 class LayerTreeHostClientForTesting;
-class TimeoutTask;
 
 // The LayerTreeTests runs with the main loop running. It instantiates a single
 // LayerTreeHostForTesting and associated LayerTreeHostImplForTesting and