Add constant color GrFP.

include/gpu/effects/GrColorProcessor.h

Index: include/gpu/effects/GrColorProcessor.h
diff --git a/include/gpu/effects/GrColorProcessor.h b/include/gpu/effects/GrColorProcessor.h
new file mode 100644
index 0000000000000000000000000000000000000000..86bb58196ca7161a919989dffa6d50e24a41436a
--- /dev/null
+++ b/include/gpu/effects/GrColorProcessor.h
@@ -0,0 +1,64 @@
+/*
+ * 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 GrColorProcessor_DEFINED
+#define GrColorProcessor_DEFINED
+
+#include "GrFragmentProcessor.h"
+
+class GrInvariantOutput;
+
+/**
+ * This is a simple GrFragmentProcessor that simply outputs a constant color. It may do one of the
+ * following with its input color: ignore it, multiply it by the constant color, multiply its alpha
+ * by the constant color and ignore the input color's r, g, and b.
+ */
+class GrColorProcessor : public GrFragmentProcessor {
+public:
+    enum InputMode {
+        kIgnore_InputMode,
+        kModulateRGBA_InputMode,
+        kModulateA_InputMode,
+
+        kLastInputMode = kModulateA_InputMode
+    };
+    static const int kInputModeCnt = kLastInputMode + 1;
+
+    static GrFragmentProcessor* Create(GrColor color, InputMode mode) {
+        return SkNEW_ARGS(GrColorProcessor, (color, mode));
+    }
+
+    ~GrColorProcessor() SK_OVERRIDE {}
+
+    const char* name() const SK_OVERRIDE { return "Color"; }
+
+    void getGLProcessorKey(const GrGLCaps&, GrProcessorKeyBuilder*) const SK_OVERRIDE;
+
+    GrGLFragmentProcessor* createGLInstance() const SK_OVERRIDE;
+
+    GrColor color() const { return fColor; }
+
+    InputMode inputMode() const { return fMode; }
+
+private:
+    GrColorProcessor(GrColor color, InputMode mode) : fColor(color), fMode(mode) {
+        this->initClassID<GrColorProcessor>();
+    }
+
+    bool onIsEqual(const GrFragmentProcessor& other) const SK_OVERRIDE;
+
+    void onComputeInvariantOutput(GrInvariantOutput* inout) const SK_OVERRIDE;
+
+    GR_DECLARE_FRAGMENT_PROCESSOR_TEST;
+
+    GrColor     fColor;
+    InputMode   fMode;
+
+    typedef GrFragmentProcessor INHERITED;
+};
+
+#endif