SkShader::asNewEffect Refactoring

The new signature is:

	bool asNewEffect(GrContext* context, const SkPaint& paint, GrColor* grColor, GrEffectRef** grEffect, const SkMatrix* localMatrixOrNull) const;

It will fix the hack for skcolorshader by modifying the GrColor parameter in SkGr::SkPaint2GrPaintShader.

BUG=skia:2646
R=jvanverth@google.com, bsalomon@google.com

Author: dandov@google.com

Review URL: https://codereview.chromium.org/318923005
diff --git a/src/effects/gradients/SkSweepGradient.h b/src/effects/gradients/SkSweepGradient.h
index 2f798e8..0b12e71 100644
--- a/src/effects/gradients/SkSweepGradient.h
+++ b/src/effects/gradients/SkSweepGradient.h
@@ -35,7 +35,8 @@
 
     virtual GradientType asAGradient(GradientInfo* info) const SK_OVERRIDE;
 
-    virtual GrEffectRef* asNewEffect(GrContext*, const SkPaint&, const SkMatrix*) const SK_OVERRIDE;
+    virtual bool asNewEffect(GrContext*, const SkPaint&, const SkMatrix*, GrColor*, GrEffectRef**)
+        const SK_OVERRIDE;
 
     SK_TO_STRING_OVERRIDE()
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkSweepGradient)