cc: Remove unused proto conversion code.

cc/trees/layer_tree.h

Index: cc/trees/layer_tree.h
diff --git a/cc/trees/layer_tree.h b/cc/trees/layer_tree.h
index fe28384d381df6cebc037d77db0428a9ad0576df..f14af5711efb1718a3193ce667f4a0d3feec101f 100644
--- a/cc/trees/layer_tree.h
+++ b/cc/trees/layer_tree.h
@@ -192,8 +192,7 @@ class CC_EXPORT LayerTree : public MutatorHostClient {
   void PushPropertiesTo(LayerTreeImpl* tree_impl,
                         float unapplied_page_scale_delta);
 
-  void ToProtobuf(proto::LayerTree* proto, bool inputs_only);
-  void FromProtobuf(const proto::LayerTree& proto);
+  void ToProtobuf(proto::LayerTree* proto);
 
   MutatorHost* mutator_host() const { return mutator_host_; }
 
@@ -216,8 +215,6 @@ class CC_EXPORT LayerTree : public MutatorHostClient {
   // ---------------------------------------------------------------------
 
  private:
-  friend class LayerTreeHostSerializationTest;
-
   // MutatorHostClient implementation.
   bool IsElementInList(ElementId element_id,
                        ElementListType list_type) const override;