Make GrGLShaderBuilder check whether GrEffect advertised that it would require the dst color or frag

src/core/SkXfermode.cpp

 
 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #include "SkXfermode.h"
@@ skipping 1340 matching lines @@
                                   setSatFunction);
 
         }
 
         typedef GrGLEffect INHERITED;
     };
 
     GR_DECLARE_EFFECT_TEST;
 
 private:
-    XferEffect(SkXfermode::Mode mode) : fMode(mode) { this->setWillReadDst(); }
+    XferEffect(SkXfermode::Mode mode) : fMode(mode) { this->setWillReadDstColor(); }
     virtual bool onIsEqual(const GrEffect& other) const SK_OVERRIDE { return true; }
 
     SkXfermode::Mode fMode;
 
     typedef GrEffect INHERITED;
 };
 
 GR_DEFINE_EFFECT_TEST(XferEffect);
 GrEffectRef* XferEffect::TestCreate(SkMWCRandom* rand,
                                     GrContext*,
@@ skipping 598 matching lines @@
     return proc16;
 }
 
 SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_START(SkXfermode)
     SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkProcCoeffXfermode)
     SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkClearXfermode)
     SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkSrcXfermode)
     SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkDstInXfermode)
     SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkDstOutXfermode)
 SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_END