Clean up locking.

native_client_sdk/src/libraries/nacl_io_test/kernel_proxy_test.cc

Index: native_client_sdk/src/libraries/nacl_io_test/kernel_proxy_test.cc
diff --git a/native_client_sdk/src/libraries/nacl_io_test/kernel_proxy_test.cc b/native_client_sdk/src/libraries/nacl_io_test/kernel_proxy_test.cc
index 70e76e17b9cade94e18a3b760d21f4e9e3aae078..2d61cbc431d0ea762f898baadc5d4fa7d5e32f05 100644
--- a/native_client_sdk/src/libraries/nacl_io_test/kernel_proxy_test.cc
+++ b/native_client_sdk/src/libraries/nacl_io_test/kernel_proxy_test.cc
@@ -38,7 +38,13 @@ namespace {
 
 class KernelProxyFriend : public KernelProxy {
  public:
-  Mount* RootMount() { return mounts_["/"].get(); }
+  Mount* RootMount() {
+    ScopedMount mnt;
+    Path path;
+
+    AcquireMountAndRelPath("/", &mnt, &path);
+    return mnt.get();
+  }
 };
 
 class KernelProxyTest : public ::testing::Test {