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/drawlooper.cpp b/gm/drawlooper.cpp
index d3a4475..67e280e 100644
--- a/gm/drawlooper.cpp
+++ b/gm/drawlooper.cpp
@@ -85,7 +85,7 @@
             paint->setStyle(gParams[i].fStyle);
             paint->setStrokeWidth(gParams[i].fWidth);
             if (gParams[i].fBlur > 0) {
-                SkMaskFilter* mf = SkBlurMaskFilter::Create(SkBlurMaskFilter::kNormal_BlurStyle,
+                SkMaskFilter* mf = SkBlurMaskFilter::Create(kNormal_SkBlurStyle,
                                          SkBlurMask::ConvertRadiusToSigma(gParams[i].fBlur));
                 paint->setMaskFilter(mf)->unref();
             }