cc/blimp: Set up the framework for state serialization.

cc/blimp/layer_tree_host_remote.h

Index: cc/blimp/layer_tree_host_remote.h
diff --git a/cc/blimp/layer_tree_host_remote.h b/cc/blimp/layer_tree_host_remote.h
index 9784a82e6fbeb04f177ed50c95c04a1a28fc72a5..7c4c28e8821b3a260a18900efada4d6ebbf92586 100644
--- a/cc/blimp/layer_tree_host_remote.h
+++ b/cc/blimp/layer_tree_host_remote.h
@@ -20,6 +20,10 @@ class SingleThreadTaskRunner;
 }  // namespace base
 
 namespace cc {
+namespace proto {
+class LayerTreeHost;
+}  // namespace proto
+
 class AnimationHost;
 class RemoteCompositorBridge;
 class LayerTreeHostClient;
@@ -103,6 +107,7 @@ class CC_EXPORT LayerTreeHostRemote : public LayerTreeHost,
   void ScheduleMainFrameIfNecessary();
   void MainFrameComplete();
   void DispatchDrawAndSwapCallbacks();
+  void SerializeCurrentState(proto::LayerTreeHost* layer_tree_host_proto);
 
   const int id_;
   int source_frame_number_ = 0;