Update {virtual,override} to follow C++11 style in src/utils.

src/utils/debugger/SkDebugCanvas.cpp

Index: src/utils/debugger/SkDebugCanvas.cpp
diff --git a/src/utils/debugger/SkDebugCanvas.cpp b/src/utils/debugger/SkDebugCanvas.cpp
index 1b50efaa325b7b6f677b869cfa4b1c3926aa0bf9..21272d7d24ed9c51703137f99f19e5cb31afce00 100644
--- a/src/utils/debugger/SkDebugCanvas.cpp
+++ b/src/utils/debugger/SkDebugCanvas.cpp
@@ -53,7 +53,7 @@ public:
 
     Factory getFactory() const override { return NULL; }
 #ifndef SK_IGNORE_TO_STRING
-    virtual void toString(SkString* str) const override { str->set("OverdrawXfermode"); }
+    void toString(SkString* str) const override { str->set("OverdrawXfermode"); }
 #endif
 };