Add GrEllipseEdgeEffect.

Adds the effect that replaces the old oval rendering code. Also hooks in code to set attribute names and indices for effects.

Author: jvanverth@google.com

Review URL: https://chromiumcodereview.appspot.com/12462008

git-svn-id: http://skia.googlecode.com/svn/trunk@8092 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/include/gpu/GrBackendEffectFactory.h b/include/gpu/GrBackendEffectFactory.h
index a291387..f5e638f 100644
--- a/include/gpu/GrBackendEffectFactory.h
+++ b/include/gpu/GrBackendEffectFactory.h
@@ -40,7 +40,8 @@
          * GrGLEffects' control. So there is a dedicated part of the key which is combined
          * automatically with the bits produced by GrGLEffect::GenKey().
          */
-        kTextureKeyBits = 6
+        kTextureKeyBits = 6,
+        kAttribKeyBits = 4
     };
 
     virtual EffectKey glEffectKey(const GrEffectStage&, const GrGLCaps&) const = 0;