Revert of Remove GP from drawstate, revision of invariant output for GP

include/gpu/GrProcessor.h

Index: include/gpu/GrProcessor.h
diff --git a/include/gpu/GrProcessor.h b/include/gpu/GrProcessor.h
index 8a8d685e518afe598a0c0e94cac45ba077c492a0..6a497e7514383ba6fa7841763a49fedcc89ce5c2 100644
--- a/include/gpu/GrProcessor.h
+++ b/include/gpu/GrProcessor.h
@@ -61,6 +61,16 @@
 
     virtual ~GrProcessor();
 
+    /**
+     * This function is used to perform optimizations. When called the invarientOuput param
+     * indicate whether the input components to this processor in the FS will have known values.
+     * In inout the validFlags member is a bitfield of GrColorComponentFlags. The isSingleComponent
+     * member indicates whether the input will be 1 or 4 bytes. The function updates the members of
+     * inout to indicate known values of its output. A component of the color member only has
+     * meaning if the corresponding bit in validFlags is set.
+     */
+    void computeInvariantOutput(GrInvariantOutput* inout) const; 
+
     /** Human-meaningful string to identify this prcoessor; may be embedded
         in generated shader code. */
     virtual const char* name() const = 0;
@@ -122,6 +132,11 @@
     uint32_t fClassID;
 
 private:
+    /** 
+     * Subclass implements this to support getConstantColorComponents(...).
+     */
+    virtual void onComputeInvariantOutput(GrInvariantOutput* inout) const = 0;
+    
     static uint32_t GenClassID() {
         // fCurrProcessorClassID has been initialized to kIllegalProcessorClassID. The
         // atomic inc returns the old value not the incremented value. So we add