Enable builtin Mojo JS modules in layout tests

content/public/common/bindings_policy.h

Index: content/public/common/bindings_policy.h
diff --git a/content/public/common/bindings_policy.h b/content/public/common/bindings_policy.h
index 9a4745c4295cff5094e4030fdbdab723c6af1441..ee3b0e87efded12a71fb718dbe1dd81e3b7c6909 100644
--- a/content/public/common/bindings_policy.h
+++ b/content/public/common/bindings_policy.h
@@ -22,6 +22,16 @@ enum BindingsPolicy {
   // metrics. (By default this isn't allowed unless the app has been started up
   // with the --enable-stats-collection-bindings switch.)
   BINDINGS_POLICY_STATS_COLLECTION = 1 << 2,
+  // Bindings that allows the JS content to access Mojo system API and
+  // ServiceRegistry modules. The system API modules are defined in
+  // //mojo/public/js and provide the ability to create Mojo primitives such as
+  // message and data pipes. The ServiceRegistry module (see
+  // //content/renderer/mojo/service_registry_js_wrapper.h) in turn allows these
+  // Mojo primitives to be used to connect to named services exposed either by
+  // the browser or testing code. These bindings should not be exposed to
+  // normal web contents and are intended only for use with WebUI and layout
+  // tests.
+  BINDINGS_POLICY_MOJO = 1 << 3,
 
 };