Make skpaint->grpaint flow work for composing draws

include/gpu/GrInvariantOutput.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 GrInvariantOutput_DEFINED
 #define GrInvariantOutput_DEFINED
 
@@ skipping 204 matching lines @@
         fIsSingleComponent = false;
         fNonMulStageFound = true;
         if (kWillNot_ReadInput == readsInput) {
             fWillUseInputColor = false;
         }
         if (kRGBA_GrColorComponentFlags == fValidFlags) {
             uint32_t a;
             if (GetAlphaAndCheckSingleChannel(color, &a)) {
                 fIsSingleComponent = true;
             }
-        } else if (kA_GrColorComponentFlag & fValidFlags) {
-            // Assuming fColor is premul means if a is 0 the color must be all 0s.
-            if (!GrColorUnpackA(fColor)) {
-                this->internalSetToTransparentBlack();
-            }
         }
         SkDEBUGCODE(this->validate());
     }
 
     void setToUnknown(ReadInput readsInput) {
         SkDEBUGCODE(this->validate());
         this->internalSetToUnknown();
         fNonMulStageFound= true;
         if (kWillNot_ReadInput == readsInput) {
             fWillUseInputColor = false;
         }
         SkDEBUGCODE(this->validate());
     }
 
     // Temporary setter to handle LCD text correctly until we improve texture pixel config queries
     // and thus can rely solely on number of coverage components for RGA vs single channel coverage.
     void setUsingLCDCoverage() {
         fIsLCDCoverage = true;
     }
 
     GrColor color() const { return fColor; }
     GrColorComponentFlags validFlags() const { return fValidFlags; }
+    bool willUseInputColor() const { return fWillUseInputColor; }
 
     /**
      * If isSingleComponent is true, then the flag values for r, g, b, and a must all be the
      * same. If the flags are all set then all color components must be equal.
      */
     SkDEBUGCODE(void validate() const;)
 
 private:
     friend class GrProcOptInfo;
 
@@ skipping 39 matching lines @@
     bool isOpaque() const {
         return ((fValidFlags & kA_GrColorComponentFlag) && 0xFF == GrColorUnpackA(fColor));
     }
 
     bool isSolidWhite() const {
         return (fValidFlags == kRGBA_GrColorComponentFlags && 0xFFFFFFFF == fColor);
     }
 
     bool isSingleComponent() const { return fIsSingleComponent; }
 
-    bool willUseInputColor() const { return fWillUseInputColor; }
     void resetWillUseInputColor() { fWillUseInputColor = true; }
 
     bool allStagesMulInput() const { return !fNonMulStageFound; }
     void resetNonMulStageFound() { fNonMulStageFound = false; }
 
     bool isLCDCoverage() const { return fIsLCDCoverage; }
 
     SkDEBUGCODE(bool colorComponentsAllEqual() const;)
     /**
      * If alpha is valid, check that any valid R,G,B values are <= A
      */
     SkDEBUGCODE(bool validPreMulColor() const;)
 
     GrColor fColor;
     GrColorComponentFlags fValidFlags;
     bool fIsSingleComponent;
     bool fNonMulStageFound;
     bool fWillUseInputColor;
     bool fIsLCDCoverage; // Temorary data member until texture pixel configs are updated
 
 };
 
 #endif