Add XP to handle the cases where we disable color write.

src/gpu/effects/GrDisableColorXP.cpp

+/*
+ * Copyright 2014 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "effects/GrDisableColorXP.h"
+#include "GrProcessor.h"
+#include "gl/GrGLXferProcessor.h"
+
+class GrGLDisableColorXP : public GrGLXferProcessor {
+public:
+    GrGLDisableColorXP(const GrProcessor&) {}
+
+    ~GrGLDisableColorXP() SK_OVERRIDE {}
+
+    void emitCode(const EmitArgs& args) SK_OVERRIDE {}
+
+    void setData(const GrGLProgramDataManager&, const GrXferProcessor&) SK_OVERRIDE {}
+
+    static void GenKey(const GrProcessor&, const GrGLCaps&, GrProcessorKeyBuilder*) {}
+
+private:
+    typedef GrGLXferProcessor INHERITED;
+};
+
+///////////////////////////////////////////////////////////////////////////////
+
+GrDisableColorXP::GrDisableColorXP() {
+    this->initClassID<GrDisableColorXP>();
+}
+
+void GrDisableColorXP::getGLProcessorKey(const GrGLCaps& caps, GrProcessorKeyBuilder* b) const {
+    GrGLDisableColorXP::GenKey(*this, caps, b);
+}
+
+GrGLXferProcessor* GrDisableColorXP::createGLInstance() const {
+    return SkNEW_ARGS(GrGLDisableColorXP, (*this));
+}
+
+void GrDisableColorXP::getBlendInfo(GrXferProcessor::BlendInfo* blendInfo) const {
+    blendInfo->fWriteColor = false;
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
+GrDisableColorXPFactory::GrDisableColorXPFactory() {
+    this->initClassID<GrDisableColorXPFactory>();
+}
+
+GrXferProcessor* GrDisableColorXPFactory::createXferProcessor(const GrProcOptInfo& colorPOI,
+                                                              const GrProcOptInfo& covPOI) const {
+    return GrDisableColorXP::Create();
+}
+
+GR_DEFINE_XP_FACTORY_TEST(GrDisableColorXPFactory);
+
+GrXPFactory* GrDisableColorXPFactory::TestCreate(SkRandom* random,
+                                                  GrContext*,
+                                                  const GrDrawTargetCaps&,
+                                                  GrTexture*[]) {
+    return GrDisableColorXPFactory::Create();
+}
+