Add interface versioning. Methods queryVersion and requireVersion.

ios/web/BUILD.gn

 # Copyright 2015 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("//ios/build/config.gni")
 import("//ios/web/js_compile.gni")
 import("//testing/test.gni")
 import("//tools/grit/grit_rule.gni")
 
 group("all_tests") {
@@ skipping 642 matching lines @@
   ]
 }
 
 grit("resources") {
   source = "ios_web_resources.grd"
   use_qualified_include = true
   outputs = [
     "grit/ios_web_resources.h",
     "ios_web_resources.pak",
   ]
+  grit_flags = [
+    "-E",
+    "root_gen_dir=" + rebase_path(root_gen_dir, root_build_dir),
+  ]
+  deps = [
+    "//mojo/public/js:bindings",
+  ]
 }