blimp: Update page load status update indicator to use first paint.

cc/trees/layer_tree_host.h

Index: cc/trees/layer_tree_host.h
diff --git a/cc/trees/layer_tree_host.h b/cc/trees/layer_tree_host.h
index e544e0cac41391df6e37492831506b9f137513c2..f0980a23b16ea377dfaaa8c4822f9f52df397af1 100644
--- a/cc/trees/layer_tree_host.h
+++ b/cc/trees/layer_tree_host.h
@@ -402,7 +402,11 @@ class CC_EXPORT LayerTreeHost : public MutatorHostClient {
   // Serializes the parts of this LayerTreeHost that is needed for a commit to a
   // protobuf message. Not all members are serialized as they are not helpful
   // for remote usage.
-  void ToProtobufForCommit(proto::LayerTreeHost* proto);
+  // The |swap_promise_list_| is transferred to the serializer in
+  // |swap_promises|.
+  void ToProtobufForCommit(
+      proto::LayerTreeHost* proto,
+      std::vector<std::unique_ptr<SwapPromise>>* swap_promises);
 
   // Deserializes the protobuf into this LayerTreeHost before a commit. The
   // expected input is a serialized remote LayerTreeHost. After deserializing