Add support for LayerTreeSettings (de)serialization

cc/trees/layer_tree_settings.h

Index: cc/trees/layer_tree_settings.h
diff --git a/cc/trees/layer_tree_settings.h b/cc/trees/layer_tree_settings.h
index 9fb59cba3b4c1f6301bf75f7eeb46ffc059eb8ec..0939ba071d76828f0f345d5010f4f850864ab073 100644
--- a/cc/trees/layer_tree_settings.h
+++ b/cc/trees/layer_tree_settings.h
@@ -18,11 +18,22 @@
 
 namespace cc {
 
+namespace proto {
+class LayerTreeSettings;
+}  // namespace proto
+
 class CC_EXPORT LayerTreeSettings {
  public:
   LayerTreeSettings();
   virtual ~LayerTreeSettings();
 
+  bool operator==(const LayerTreeSettings& other) const;
+
+  void ToProtobuf(proto::LayerTreeSettings* proto) const;
+  void FromProtobuf(const proto::LayerTreeSettings& proto);
+
+  SchedulerSettings ToSchedulerSettings() const;
+
   RendererSettings renderer_settings;
   bool single_thread_proxy_scheduler;
   bool use_external_begin_frame_source;
@@ -80,8 +91,6 @@ class CC_EXPORT LayerTreeSettings {
   ManagedMemoryPolicy memory_policy_;
 
   LayerTreeDebugState initial_debug_state;
-
-  SchedulerSettings ToSchedulerSettings() const;
 };
 
 }  // namespace cc