Update XPF invariant info to not account for conflation

include/gpu/GrXferProcessor.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 GrXferProcessor_DEFINED
 #define GrXferProcessor_DEFINED
 
@@ skipping 345 matching lines @@
                                          const DstTexture*,
                                          const GrCaps& caps) const;
 
     /**
      * This function returns true if the GrXferProcessor generated from this factory will be able to
      * correctly blend when using RGB coverage. The knownColor and knownColorFlags represent the
      * final computed color from the color stages.
      */
     virtual bool supportsRGBCoverage(GrColor knownColor, uint32_t knownColorFlags) const = 0;
 
-    struct InvariantOutput {
-        bool        fWillBlendWithDst;
-        GrColor     fBlendedColor;
-        uint32_t    fBlendedColorFlags;
+    /**
+     * Known color information after blending, but before accounting for any coverage.
+     */
+    struct InvariantBlendedColor {
+        bool                     fWillBlendWithDst;
+        GrColor                  fKnownColor;
+        GrColorComponentFlags    fKnownColorFlags;
     };
 
     /** 
-     * This function returns known information about the output of the xfer processor produced by
-     * this xp factory. The invariant color information returned by this function refers to the
-     * final color produced after all blending.
+     * Returns information about the output color, produced by XPs from this factory, that will be
+     * known after blending. Note that we can conflate coverage and color, so the actual values
+     * written to pixels with partial coverage may not always seem consistent with the invariant
+     * information returned by this function.
      */
-    virtual void getInvariantOutput(const GrProcOptInfo& colorPOI, const GrProcOptInfo& coveragePOI,
-                                    InvariantOutput*) const = 0;
+    virtual void getInvariantBlendedColor(const GrProcOptInfo& colorPOI,
+                                          InvariantBlendedColor*) const = 0;
 
     bool willNeedDstTexture(const GrCaps& caps, const GrProcOptInfo& colorPOI,
                             const GrProcOptInfo& coveragePOI) const;
 
     bool isEqual(const GrXPFactory& that) const {
         if (this->classID() != that.classID()) {
             return false;
         }
         return this->onIsEqual(that);
     }
@@ skipping 45 matching lines @@
     enum {
         kIllegalXPFClassID = 0,
     };
     static int32_t gCurrXPFClassID;
 
     typedef GrProgramElement INHERITED;
 };
 
 #endif