Label `willReadDstColor` argument to GrXferProcessor ctor.

This makes it much easier to search through the code and find places
where `willReadDstColor` is set.

Change-Id: I94077d2ce2cacf35c84f7ff6ba2da3c5c3bab15c
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/410677
Auto-Submit: John Stiles <johnstiles@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
diff --git a/src/gpu/effects/GrCustomXfermode.cpp b/src/gpu/effects/GrCustomXfermode.cpp
index 4750511..30c7077 100644
--- a/src/gpu/effects/GrCustomXfermode.cpp
+++ b/src/gpu/effects/GrCustomXfermode.cpp
@@ -78,7 +78,7 @@
         , fHWBlendEquation(hwBlendEquation) {}
 
     CustomXP(SkBlendMode mode, GrProcessorAnalysisCoverage coverage)
-            : INHERITED(kCustomXP_ClassID, true, coverage)
+            : INHERITED(kCustomXP_ClassID, /*willReadDstColor=*/true, coverage)
             , fMode(mode)
             , fHWBlendEquation(kIllegal_GrBlendEquation) {
     }
diff --git a/src/gpu/effects/GrPorterDuffXferProcessor.cpp b/src/gpu/effects/GrPorterDuffXferProcessor.cpp
index 1e0591f..774b8e8 100644
--- a/src/gpu/effects/GrPorterDuffXferProcessor.cpp
+++ b/src/gpu/effects/GrPorterDuffXferProcessor.cpp
@@ -374,7 +374,7 @@
 class PorterDuffXferProcessor : public GrXferProcessor {
 public:
     PorterDuffXferProcessor(BlendFormula blendFormula, GrProcessorAnalysisCoverage coverage)
-            : INHERITED(kPorterDuffXferProcessor_ClassID, false, coverage)
+            : INHERITED(kPorterDuffXferProcessor_ClassID, /*willReadDstColor=*/false, coverage)
             , fBlendFormula(blendFormula) {
     }
 
@@ -483,7 +483,7 @@
 class ShaderPDXferProcessor : public GrXferProcessor {
 public:
     ShaderPDXferProcessor(SkBlendMode xfermode, GrProcessorAnalysisCoverage coverage)
-            : INHERITED(kShaderPDXferProcessor_ClassID, true, coverage)
+            : INHERITED(kShaderPDXferProcessor_ClassID, /*willReadDstColor=*/true, coverage)
             , fXfermode(xfermode) {
     }
 
@@ -630,7 +630,8 @@
 ///////////////////////////////////////////////////////////////////////////////
 
 PDLCDXferProcessor::PDLCDXferProcessor(const SkPMColor4f& blendConstant, float alpha)
-    : INHERITED(kPDLCDXferProcessor_ClassID, false, GrProcessorAnalysisCoverage::kLCD)
+    : INHERITED(kPDLCDXferProcessor_ClassID, /*willReadDstColor=*/false,
+                GrProcessorAnalysisCoverage::kLCD)
     , fBlendConstant(blendConstant)
     , fAlpha(alpha) {
 }