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/SampleTextAlpha.cpp b/samplecode/SampleTextAlpha.cpp
index 2732452..fcef92f 100644
--- a/samplecode/SampleTextAlpha.cpp
+++ b/samplecode/SampleTextAlpha.cpp
@@ -70,7 +70,7 @@
 
         paint.setARGB(fByte, 0xFF, 0xFF, 0xFF);
 
-        paint.setMaskFilter(SkBlurMaskFilter::Create(SkBlurMaskFilter::kNormal_BlurStyle,
+        paint.setMaskFilter(SkBlurMaskFilter::Create(kNormal_SkBlurStyle,
                                     SkBlurMask::ConvertRadiusToSigma(SkIntToScalar(3))));
         paint.getMaskFilter()->unref();