add asAShadowBlur for android to drawlooper

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

Review URL: https://codereview.chromium.org/253633003

git-svn-id: http://skia.googlecode.com/svn/trunk@14431 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/include/effects/SkLayerDrawLooper.h b/include/effects/SkLayerDrawLooper.h
index fe660a8..ac56e28 100644
--- a/include/effects/SkLayerDrawLooper.h
+++ b/include/effects/SkLayerDrawLooper.h
@@ -77,6 +77,8 @@
 
     virtual size_t contextSize() const SK_OVERRIDE { return sizeof(LayerDrawLooperContext); }
 
+    virtual bool asABlurShadow(BlurShadowRec* rec) const SK_OVERRIDE;
+
     SK_TO_STRING_OVERRIDE()
 
     /// Implements Flattenable.