Enable mojo js tests which depend on mojom.js files in gen/.

mojo/common/test/test_utils_win.cc

 // Copyright 2014 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 "mojo/common/test/test_utils.h"
 
 #include <windows.h>
 
+#include "base/base_paths.h"
+#include "base/path_service.h"
+#include "base/strings/string_util.h"
 #include "mojo/embedder/platform_handle.h"
 
 namespace mojo {
 namespace test {
 
 bool BlockingWrite(const embedder::PlatformHandle& handle,
                    const void* buffer,
                    size_t bytes_to_write,
                    size_t* bytes_written) {
   OVERLAPPED overlapped = { 0 };
@@ skipping 50 matching lines @@
                              TRUE)) {
       *bytes_read = 0;
       return true;
     }
   }
 
   *bytes_read = bytes_read_dword;
   return true;
 }
 
+base::FilePath GetFilePathForJSResource(const std::string& path) {
+  std::string binding_path = "gen/" + path + ".js";
+  base::ReplaceChars(binding_path, "//", "\\", &binding_path);
+  base::FilePath exe_dir;
+  PathService::Get(base::DIR_EXE, &exe_dir);
+  return exe_dir.AppendASCII(binding_path);
+}
+
 }  // namespace test
 }  // namespace mojo