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

mojo/common/test/test_utils_posix.cc

Index: mojo/common/test/test_utils_posix.cc
diff --git a/mojo/common/test/test_utils_posix.cc b/mojo/common/test/test_utils_posix.cc
index 254d0a87690988b035eea6608e55f118a812a75d..b99ad3b636e2eaa97588dcb83d96aed1254290ae 100644
--- a/mojo/common/test/test_utils_posix.cc
+++ b/mojo/common/test/test_utils_posix.cc
@@ -7,6 +7,8 @@
 #include <fcntl.h>
 #include <unistd.h>
 
+#include "base/base_paths.h"
+#include "base/path_service.h"
 #include "base/posix/eintr_wrapper.h"
 #include "mojo/embedder/platform_handle.h"
 
@@ -73,5 +75,12 @@ bool NonBlockingRead(const embedder::PlatformHandle& handle,
   return true;
 }
 
+base::FilePath GetFilePathForJSResource(const std::string& path) {
+  std::string binding_path = "gen/" + path + ".js";
+  base::FilePath exe_dir;
+  PathService::Get(base::DIR_EXE, &exe_dir);
+  return exe_dir.AppendASCII(binding_path);
+}
+
 }  // namespace test
 }  // namespace mojo