Fix warning

Bug: 21608208
Change-Id: I1d1cf1fbc8c0a4561bf76e307c56be580fb4baef
diff --git a/libs/hwui/FrameInfo.cpp b/libs/hwui/FrameInfo.cpp
index c24833b..85998f1 100644
--- a/libs/hwui/FrameInfo.cpp
+++ b/libs/hwui/FrameInfo.cpp
@@ -20,7 +20,7 @@
 namespace android {
 namespace uirenderer {
 
-std::string FrameInfoNames[] = {
+const std::string FrameInfoNames[] = {
     "Flags",
     "IntendedVsync",
     "Vsync",