Update XPF invariant info to not account for conflation

src/gpu/GrPipelineBuilder.h

Index: src/gpu/GrPipelineBuilder.h
diff --git a/src/gpu/GrPipelineBuilder.h b/src/gpu/GrPipelineBuilder.h
index 09b4f91e7304760e8b386c579bf8af1aeeb25ba7..dbbf98a815a8dedfd418743b61814a3622baa101 100644
--- a/src/gpu/GrPipelineBuilder.h
+++ b/src/gpu/GrPipelineBuilder.h
@@ -139,10 +139,12 @@ public:
     ////
 
     /**
-     * This function returns true if the render target destination pixel values will be read for
-     * blending during draw.
+     * Returns true if this pipeline's color output will be affected by the existing render target
+     * destination pixel values (meaning we need to be careful with overlapping draws). Note that we
+     * can conflate coverage and color, so the destination color may still bleed into pixels that
+     * have partial coverage, even if this function returns false.
      */
-    bool willBlendWithDst(const GrPrimitiveProcessor*) const;
+    bool willColorBlendWithDst(const GrPrimitiveProcessor*) const;
 
     /**
      * Installs a GrXPFactory. This object controls how src color, fractional pixel coverage,
@@ -387,7 +389,7 @@ private:
     //
     // canUseFracCoveragePrimProc() - Called in regular skia draw, caches results but only for a
     //                                specific color and coverage.  May be called multiple times
-    // willBlendWithDst() - only called by Nvpr, does not cache results
+    // willColorBlendWithDst() - only called by Nvpr, does not cache results
     // GrOptDrawState constructor - never caches results
 
     /**