Add Store+Sync to reading list.

ios/chrome/browser/reading_list/proto/BUILD.gn

Index: ios/chrome/browser/reading_list/proto/BUILD.gn
diff --git a/ios/chrome/browser/reading_list/proto/BUILD.gn b/ios/chrome/browser/reading_list/proto/BUILD.gn
new file mode 100644
index 0000000000000000000000000000000000000000..927a5eea83e167675b2cb6fee3186b0fced0cffa
--- /dev/null
+++ b/ios/chrome/browser/reading_list/proto/BUILD.gn
@@ -0,0 +1,14 @@
+# Copyright 2016 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import("//third_party/protobuf/proto_library.gni")
+
+proto_library("proto") {
+  sources = [
+    "reading_list.proto",
+  ]
+  deps = [
+    "//components/sync/protocol",
+  ]
+}