cc: Split Proxy to eliminate unnecessary dependencies on the impl side

cc/test/fake_layer_tree_host_impl.cc

Index: cc/test/fake_layer_tree_host_impl.cc
diff --git a/cc/test/fake_layer_tree_host_impl.cc b/cc/test/fake_layer_tree_host_impl.cc
index e210a76e63c127b591df9eb4cb8d5c5adbf4b8cb..96d4aa64eed066880f8b8a2b64a4670e163d20d8 100644
--- a/cc/test/fake_layer_tree_host_impl.cc
+++ b/cc/test/fake_layer_tree_host_impl.cc
@@ -9,34 +9,34 @@
 
 namespace cc {
 
-FakeLayerTreeHostImpl::FakeLayerTreeHostImpl(Proxy* proxy,
+FakeLayerTreeHostImpl::FakeLayerTreeHostImpl(ThreadVerifier* thread_verifier,
                                              SharedBitmapManager* manager,
                                              TaskGraphRunner* task_graph_runner)
     : FakeLayerTreeHostImpl(LayerTreeSettings(),
-                            proxy,
+                            thread_verifier,
                             manager,
                             task_graph_runner,
                             nullptr) {}
 
 FakeLayerTreeHostImpl::FakeLayerTreeHostImpl(const LayerTreeSettings& settings,
-                                             Proxy* proxy,
+                                             ThreadVerifier* thread_verifier,
                                              SharedBitmapManager* manager,
                                              TaskGraphRunner* task_graph_runner)
     : FakeLayerTreeHostImpl(settings,
-                            proxy,
+                            thread_verifier,
                             manager,
                             task_graph_runner,
                             nullptr) {}
 
 FakeLayerTreeHostImpl::FakeLayerTreeHostImpl(
     const LayerTreeSettings& settings,
-    Proxy* proxy,
+    ThreadVerifier* thread_verifier,
     SharedBitmapManager* manager,
     TaskGraphRunner* task_graph_runner,
     gpu::GpuMemoryBufferManager* gpu_memory_buffer_manager)
     : LayerTreeHostImpl(settings,
                         &client_,
-                        proxy,
+                        thread_verifier,
                         &stats_instrumentation_,
                         manager,
                         gpu_memory_buffer_manager,