Add interface to SkXfermode to return a GrEffect and blend coeffs.

src/gpu/SkGpuDevice.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkGpuDevice.h"
 
 #include "effects/GrTextureDomainEffect.h"
@@ skipping 466 matching lines @@
                                     bool constantColor,
                                     GrPaint* grPaint) {
 
     grPaint->setDither(skPaint.isDither());
     grPaint->setAntiAlias(skPaint.isAntiAlias());
 
     SkXfermode::Coeff sm = SkXfermode::kOne_Coeff;
     SkXfermode::Coeff dm = SkXfermode::kISA_Coeff;
 
     SkXfermode* mode = skPaint.getXfermode();
-    if (mode) {
-        if (!mode->asCoeff(&sm, &dm)) {
-            //SkDEBUGCODE(SkDebugf("Unsupported xfer mode.\n");)
+    GrEffectRef* xferEffect;
+    if (SkXfermode::AsNewEffect(mode, dev->context(), &xferEffect, &sm, &dm)) {
+        // We're not ready for xfermode effects yet
+        GrAssert(NULL == xferEffect);
+    } else {
+        //SkDEBUGCODE(SkDebugf("Unsupported xfer mode.\n");)
 #if 0
-            return false;
+        return false;
 #endif
-        }
     }
     grPaint->setBlendFunc(sk_blend_to_grblend(sm), sk_blend_to_grblend(dm));
 
     if (justAlpha) {
         uint8_t alpha = skPaint.getAlpha();
         grPaint->setColor(GrColorPackRGBA(alpha, alpha, alpha, alpha));
         // justAlpha is currently set to true only if there is a texture,
         // so constantColor should not also be true.
         GrAssert(!constantColor);
     } else {
@@ skipping 1330 matching lines @@
                          GrTexture* texture,
                          bool needClear)
     : SkDevice(make_bitmap(context, texture->asRenderTarget())) {
 
     GrAssert(texture && texture->asRenderTarget());
     // This constructor is called from onCreateCompatibleDevice. It has locked the RT in the texture
     // cache. We pass true for the third argument so that it will get unlocked.
     this->initFromRenderTarget(context, texture->asRenderTarget(), true);
     fNeedClear = needClear;
 }