Enable builtin Mojo JS modules in layout tests

content/renderer/render_view_impl.cc

Index: content/renderer/render_view_impl.cc
diff --git a/content/renderer/render_view_impl.cc b/content/renderer/render_view_impl.cc
index 84e6d1af9bb17da005014f5b438e4377adf6c9d2..6d1ad358a42b21c34c9d25e0823ff9b543d056f0 100644
--- a/content/renderer/render_view_impl.cc
+++ b/content/renderer/render_view_impl.cc
@@ -2359,8 +2359,14 @@ void RenderViewImpl::OnAllowBindings(int enabled_bindings_flags) {
       !(enabled_bindings_ & BINDINGS_POLICY_WEB_UI)) {
     // WebUIExtensionData deletes itself when we're destroyed.
     new WebUIExtensionData(this);
+  }
 
-    if (main_render_frame_)
+  if (main_render_frame_ &&
+      !(enabled_bindings_ & (BINDINGS_POLICY_WEB_UI | BINDINGS_POLICY_MOJO)) &&
+       (enabled_bindings_flags &
+            (BINDINGS_POLICY_WEB_UI | BINDINGS_POLICY_MOJO))) {

[Charlie Reis, 2016/01/26 01:01:02]

Looks right, but would one of your tests catch it if there were a typo in here? 
(Seems like an easy place for a typo to slip by.)  I'm guessing the layout test
would?

[Ken Rockot(use gerrit already), 2016/01/26 01:32:55]

Yeah - the layout tests cover the affirmative case (i.e. it's set when it should
be). There are already existing tests for WebUI which test the negative case,
i.e. that no extra bindings flags are set when WebUI is not enabled.

I think we'd have to add a separate test here if we ever wanted to expose Mojo
bindings beyond WebUI and layout tests, but I seriously doubt we'll ever do
that.

+      // Enable Mojo bindings iff either WebUI or Mojo bindings are being added
+      // to the policy and neither was present before.
       main_render_frame_->EnableMojoBindings();
   }