compositor-worker: Initialize CW machinery plumbing to compositor and fire CW rAF callbacks.

cc/test/fake_proxy.cc

Index: cc/test/fake_proxy.cc
diff --git a/cc/test/fake_proxy.cc b/cc/test/fake_proxy.cc
index cc254eb31f50b7d2f82579ffe334e5e689385742..080be12aa705d381db576138460e117896f83c8a 100644
--- a/cc/test/fake_proxy.cc
+++ b/cc/test/fake_proxy.cc
@@ -4,6 +4,8 @@
 
 #include "cc/test/fake_proxy.h"
 
+#include "cc/animation/layer_tree_mutator.h"
+
 namespace cc {
 
 void FakeProxy::SetLayerTreeHost(LayerTreeHost* host) {
@@ -30,6 +32,8 @@ bool FakeProxy::BeginMainFrameRequested() const { return false; }
 
 bool FakeProxy::CommitRequested() const { return false; }
 
+void FakeProxy::SetMutator(std::unique_ptr<LayerTreeMutator> mutator) {}
+
 bool FakeProxy::SupportsImplScrolling() const {
   return true;
 }