Introduce different repo types (git and gitiles)

recipe_engine/package.proto

Index: recipe_engine/package.proto
diff --git a/recipe_engine/package.proto b/recipe_engine/package.proto
index 3b738204458fb15bddf3133e67ccc5772e286cd1..40345018b765b07a1203a46fadf7a5478ce6c635 100644
--- a/recipe_engine/package.proto
+++ b/recipe_engine/package.proto
@@ -1,5 +1,10 @@
-// NOTE: this must be kept in sync with
-// https://github.com/luci/luci-go/blob/master/client/cmd/kitchen/proto/package.proto
+// Copyright 2016 The LUCI Authors. All rights reserved.
+// Use of this source code is governed under the Apache License, Version 2.0
+// that can be found in the LICENSE file.
+
+// Recompile with libprotoc 2.5.0:
+// protoc -I recipe_engine recipe_engine/package.proto --python_out=recipe_engine
+
 syntax = "proto2";
 
 package recipe_engine;
@@ -12,6 +17,12 @@ message DepSpec {
 
   // Treat a subtree of a repo as a whole repo unto itself.
   optional string path_override = 5;
+
+  enum RepoType {
+    GIT = 0;
+    GITILES = 1;
+  }
+  optional RepoType repo_type = 6 [default = GIT];
 }
 
 message Package {