Create an optimized draw state but not hooked in yet to gpu pipeline

src/gpu/GrOptDrawState.h

+/*
+ * Copyright 2014 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef GrOptDrawState_DEFINED
+#define GrOptDrawState_DEFINED
+
+#include "GrRODrawState.h"
+
+class GrDrawState;
+
+/**
+ * Subclass of GrRODrawState that holds an optimized version of a GrDrawState. Like it's parent
+ * it is meant to be an immutable class, and simply adds a few helpful data members not in the
+ * base class.
+ */
+class GrOptDrawState : public GrRODrawState {
+public:
+    /**
+     * Constructs and optimized drawState out of a GrRODrawState.
+     */
+    explicit GrOptDrawState(const GrDrawState& drawState);
+
+    bool operator== (const GrOptDrawState& that) const;
+
+private:
+    /*
+     * Loops through all the color stage effects to check if the stage will ignore color input or
+     * always output a constant color. In the ignore color input case we can ignore all previous
+     * stages. In the constant color case, we can ignore all previous stages and
+     * the current one and set the state color to the constant color. Once we determine the so
+     * called first effective stage, we copy all the effective stages into our optimized
+     * state.
+     */
+    void copyEffectiveColorStages(const GrDrawState& ds);
+
+    /*
+     * Loops through all the coverage stage effects to check if the stage will ignore color input.
+     * If a coverage stage will ignore input, then we can ignore all coverage stages before it. We
+     * loop to determine the first effective coverage stage, and then copy all of our effective
+     * coverage stages into our optimized state.
+     */
+    void copyEffectiveCoverageStages(const GrDrawState& ds);
+
+    /*
+     * This function takes in a flag and removes the corresponding fixed function vertex attributes.
+     * The flags are in the same order as GrVertexAttribBinding array. If bit i of removeVAFlags is
+     * set, then vertex attributes with binding (GrVertexAttribute)i will be removed.
+     */
+    void removeFixedFunctionVertexAttribs(uint8_t removeVAFlags);
+
+    void removeColorVertexAttrib();
+
+    // These flags are needed to protect the code from creating an unused uniform color/coverage
+    // which will cause shader compiler errors.
+    bool            fInputColorIsUsed;
+    bool            fInputCoverageIsUsed;
+
+    SkAutoSTArray<4, GrVertexAttrib> fOptVA;
+
+    typedef GrRODrawState INHERITED;
+};
+
+#endif