cc: Send shared variables between main and impl side using the channel

cc/test/layer_tree_test.cc

Index: cc/test/layer_tree_test.cc
diff --git a/cc/test/layer_tree_test.cc b/cc/test/layer_tree_test.cc
index 8207c4aee407d149847b71899bee06103274cd82..5837e3eb0549e918ce3121a111484b4010939057 100644
--- a/cc/test/layer_tree_test.cc
+++ b/cc/test/layer_tree_test.cc
@@ -181,6 +181,11 @@ class ThreadProxyForTest : public ThreadProxy {
     test_hooks_->SendBeginMainFrameNotExpectedSoon();
   }
 
+  void DidActivateSyncTree() override {
+    ThreadProxy::DidActivateSyncTree();
+    test_hooks_->DidActivateSyncTree();
+  }
+
   void SetThrottleFrameProductionOnImpl(bool throttle) override {
     ThreadProxy::SetThrottleFrameProductionOnImpl(throttle);
     test_hooks_->SetThrottleFrameProductionOnImpl(throttle);
@@ -248,11 +253,25 @@ class ThreadProxyForTest : public ThreadProxy {
     test_hooks_->FinishGLOnImpl();
   }
 
-  void StartCommitOnImpl(CompletionEvent* completion) override {
-    ThreadProxy::StartCommitOnImpl(completion);
+  void StartCommitOnImpl(CompletionEvent* completion,
+                         LayerTreeHost* layer_tree_host,
+                         bool hold_commit_for_activation) override {
+    ThreadProxy::StartCommitOnImpl(completion, layer_tree_host,
+                                   hold_commit_for_activation);
     test_hooks_->StartCommitOnImpl();
   }
 
+  void InitializeImplOnImpl(CompletionEvent* completion,
+                            LayerTreeHost* layer_tree_host) override {
+    ThreadProxy::InitializeImplOnImpl(completion, layer_tree_host);
+    test_hooks_->InitializeImplOnImpl();
+  }
+
+  void LayerTreeHostClosedOnImpl(CompletionEvent* completion) override {
+    test_hooks_->WillCloseLayerTreeHostOnImpl();
+    ThreadProxy::LayerTreeHostClosedOnImpl(completion);
+  }
+
   void DidCompleteSwapBuffers() override {
     ThreadProxy::DidCompleteSwapBuffers();
     test_hooks_->ReceivedDidCompleteSwapBuffers();