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

mojo/common/test/test_utils.h

Index: mojo/common/test/test_utils.h
diff --git a/mojo/common/test/test_utils.h b/mojo/common/test/test_utils.h
index 369e2bfc6f068a87d2ccd60c51bbb9389fd37d4d..6b9be227ad7191357a37e4dd2a41bcae4352f726 100644
--- a/mojo/common/test/test_utils.h
+++ b/mojo/common/test/test_utils.h
@@ -7,6 +7,10 @@
 
 #include <stddef.h>
 
+#include <string>
+
+#include "base/files/file_path.h"
+
 namespace mojo {
 
 namespace embedder {
@@ -38,6 +42,9 @@ bool NonBlockingRead(const embedder::PlatformHandle& handle,
                      size_t buffer_size,
                      size_t* bytes_read);
 
+// Returns the path to the mojom js bindings file.
+base::FilePath GetFilePathForJSResource(const std::string& path);
+
 }  // namespace test
 }  // namespace mojo