Move XferEffects class to GrCustomXfermode file

src/gpu/effects/GrCustomXfermodePriv.h

+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef GrCustomXfermodePriv_DEFINED
+#define GrCustomXfermodePriv_DEFINED
+
+#include "GrCoordTransform.h"
+#include "GrFragmentProcessor.h"
+#include "GrTextureAccess.h"
+#include "SkXfermode.h"
+
+class GrGLCaps;
+class GrGLFragmentProcessor;
+class GrInvariantOutput;
+class GrProcessorKeyBuilder;
+class GrTexture;
+
+///////////////////////////////////////////////////////////////////////////////
+// Fragment Processor
+///////////////////////////////////////////////////////////////////////////////
+
+class GrCustomXferFP : public GrFragmentProcessor {
+public:
+    GrCustomXferFP(SkXfermode::Mode mode, GrTexture* background);
+
+    void getGLProcessorKey(const GrGLCaps& caps, GrProcessorKeyBuilder* b) const SK_OVERRIDE; 
+
+    GrGLFragmentProcessor* createGLInstance() const SK_OVERRIDE;
+
+    const char* name() const SK_OVERRIDE { return "Custom Xfermode"; }
+
+    SkXfermode::Mode mode() const { return fMode; }
+    const GrTextureAccess&  backgroundAccess() const { return fBackgroundAccess; }
+
+private:
+    bool onIsEqual(const GrFragmentProcessor& other) const SK_OVERRIDE; 
+
+    void onComputeInvariantOutput(GrInvariantOutput* inout) const SK_OVERRIDE;
+
+    GR_DECLARE_FRAGMENT_PROCESSOR_TEST;
+
+    SkXfermode::Mode fMode;
+    GrCoordTransform fBackgroundTransform;
+    GrTextureAccess  fBackgroundAccess;
+
+    typedef GrFragmentProcessor INHERITED;
+};
+
+#endif
+