Mojo: Log an error when we fail to find a JS module.

gin/modules/file_module_provider.cc

 // Copyright 2013 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.
 
 #include "gin/modules/file_module_provider.h"
 
 #include "base/bind.h"
 #include "base/file_util.h"
 #include "base/message_loop/message_loop.h"
 #include "base/strings/string_split.h"
@@ skipping 22 matching lines @@
 
   for (size_t i = 0; i < search_paths.size(); ++i) {
     std::string source;
     if (!ReadFileToString(search_paths[i].Append(path), &source))
       continue;
 
     Runner::Scope scope(runner.get());
     runner->Run(source, id);
     return;
   }
+  LOG(ERROR) << "Failed to load module from disk: " << id;
 }
 
 }  // namespace
 
 FileModuleProvider::FileModuleProvider(
     const std::vector<base::FilePath>& search_paths)
     : search_paths_(search_paths) {
 }
 
 FileModuleProvider::~FileModuleProvider() {
 }
 
 void FileModuleProvider::AttempToLoadModules(
     Runner* runner, const std::set<std::string>& ids) {
   std::set<std::string> modules = ids;
   for (std::set<std::string>::const_iterator it = modules.begin();
        it != modules.end(); ++it) {
     const std::string& id = *it;
     if (attempted_ids_.count(id))
       continue;
     attempted_ids_.insert(id);
     base::MessageLoop::current()->PostTask(FROM_HERE, base::Bind(
         AttempToLoadModule, runner->GetWeakPtr(), search_paths_, id));
   }
 }
 
 }  // namespace gin