Handle JS mojo module fetch failures gracefully.

content/renderer/mojo_context_state.h

Index: content/renderer/mojo_context_state.h
diff --git a/content/renderer/mojo_context_state.h b/content/renderer/mojo_context_state.h
index c9af2621868dd1d0dfa7718d7f90c313b2eb1710..eaca53069975690bb5f43c67afe1a891573bf879 100644
--- a/content/renderer/mojo_context_state.h
+++ b/content/renderer/mojo_context_state.h
@@ -55,6 +55,7 @@ class MojoContextState : public gin::ModuleRegistryObserver {
 
   // Callback once a module has finished downloading. Passes data to |runner_|.
   void OnFetchModuleComplete(ResourceFetcher* fetcher,
+                             const std::string& id,
                              const blink::WebURLResponse& response,
                              const std::string& data);