Fix sky include guards to match Chromium style

sky/engine/wtf/dtoa/utils.h

Index: sky/engine/wtf/dtoa/utils.h
diff --git a/sky/engine/wtf/dtoa/utils.h b/sky/engine/wtf/dtoa/utils.h
index eba49dafeeffcc0076a88fc34da24509c66e1d91..a22ca1b6367e2236b6e8b47bc07fcc72f18e7bbb 100644
--- a/sky/engine/wtf/dtoa/utils.h
+++ b/sky/engine/wtf/dtoa/utils.h
@@ -25,8 +25,8 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-#ifndef DOUBLE_CONVERSION_UTILS_H_
-#define DOUBLE_CONVERSION_UTILS_H_
+#ifndef SKY_ENGINE_WTF_DTOA_UTILS_H_
+#define SKY_ENGINE_WTF_DTOA_UTILS_H_
 
 #include <string.h>
 #include "sky/engine/wtf/Assertions.h"
@@ -282,4 +282,4 @@ namespace double_conversion {
 
 } // namespace WTF
 
-#endif  // DOUBLE_CONVERSION_UTILS_H_
+#endif  // SKY_ENGINE_WTF_DTOA_UTILS_H_