Rename GrSamplerState to GrEffectStage.

R=robertphillips@google.com
Review URL: https://codereview.appspot.com/6777053

git-svn-id: http://skia.googlecode.com/svn/trunk@6135 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/effects/gradients/SkGradientShaderPriv.h b/src/effects/gradients/SkGradientShaderPriv.h
index 6bb0a60..194ff8c 100644
--- a/src/effects/gradients/SkGradientShaderPriv.h
+++ b/src/effects/gradients/SkGradientShaderPriv.h
@@ -194,7 +194,7 @@
 
 #include "gl/GrGLEffect.h"
 
-class GrSamplerState;
+class GrEffectStage;
 class GrBackendEffectFactory;
 
 /*