move common blur types into central header

BUG=skia:
R=scroggo@google.com, djsollen@google.com

Author: reed@google.com

Review URL: https://codereview.chromium.org/253833002

git-svn-id: http://skia.googlecode.com/svn/trunk@14411 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/gm/megalooper.cpp b/gm/megalooper.cpp
index e825550..ae92971 100644
--- a/gm/megalooper.cpp
+++ b/gm/megalooper.cpp
@@ -113,8 +113,7 @@
     SkMaskFilter* createBlur() {
         static const SkScalar kBlurSigma = SkBlurMask::ConvertRadiusToSigma(SkIntToScalar(25));
 
-        return SkBlurMaskFilter::Create(SkBlurMaskFilter::kNormal_BlurStyle,
-                                        kBlurSigma,
+        return SkBlurMaskFilter::Create(kNormal_SkBlurStyle, kBlurSigma,
                                         SkBlurMaskFilter::kHighQuality_BlurFlag);
     }