Fix cpplint errors.

Change-Id: I21f7423ebe69a77d456b0d318de73448489d2df4
diff --git a/runtime/gc/space/malloc_space.h b/runtime/gc/space/malloc_space.h
index bd21a4d..189f01c 100644
--- a/runtime/gc/space/malloc_space.h
+++ b/runtime/gc/space/malloc_space.h
@@ -181,6 +181,7 @@
 
   friend class collector::MarkSweep;
 
+ private:
   DISALLOW_COPY_AND_ASSIGN(MallocSpace);
 };
 
@@ -188,4 +189,4 @@
 }  // namespace gc
 }  // namespace art
 
-#endif  // ART_RUNTIME_GC_SPACE_DLMALLOC_SPACE_H_
+#endif  // ART_RUNTIME_GC_SPACE_MALLOC_SPACE_H_