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/samplecode/SampleSlides.cpp b/samplecode/SampleSlides.cpp
index ece9684..d828ae6 100644
--- a/samplecode/SampleSlides.cpp
+++ b/samplecode/SampleSlides.cpp
@@ -478,7 +478,7 @@
 
 static void r0(SkLayerRasterizer::Builder* rastBuilder, SkPaint& p)
 {
-    p.setMaskFilter(SkBlurMaskFilter::Create(SkBlurMaskFilter::kNormal_BlurStyle,
+    p.setMaskFilter(SkBlurMaskFilter::Create(kNormal_SkBlurStyle,
                                              SkBlurMask::ConvertRadiusToSigma(SkIntToScalar(3))))->unref();
     rastBuilder->addLayer(p, SkIntToScalar(3), SkIntToScalar(3));