Only discard for XP dstCopies if we have a coverage value.

src/gpu/effects/GrDisableColorXP.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "effects/GrDisableColorXP.h"
 #include "GrProcessor.h"
 #include "gl/GrGLXferProcessor.h"
@@ skipping 11 matching lines @@
     }
 
     ~DisableColorXP() override {};
 
     const char* name() const override { return "Disable Color"; }
 
     GrGLXferProcessor* createGLInstance() const override;
 
     bool hasSecondaryOutput() const override { return false; }
 
-    GrXferProcessor::OptFlags getOptimizations(const GrProcOptInfo& colorPOI,
-                                               const GrProcOptInfo& coveragePOI,
-                                               bool doesStencilWrite,
-                                               GrColor* color,
-                                               const GrDrawTargetCaps& caps) override {
-        return GrXferProcessor::kIgnoreColor_OptFlag | GrXferProcessor::kIgnoreCoverage_OptFlag;
-    }
-
 private:
     DisableColorXP();
 
+    GrXferProcessor::OptFlags onGetOptimizations(const GrProcOptInfo& colorPOI,
+                                                 const GrProcOptInfo& coveragePOI,
+                                                 bool doesStencilWrite,
+                                                 GrColor* color,
+                                                 const GrDrawTargetCaps& caps) override {
+        return GrXferProcessor::kIgnoreColor_OptFlag | GrXferProcessor::kIgnoreCoverage_OptFlag;
+    }
+
     void onGetGLProcessorKey(const GrGLSLCaps& caps, GrProcessorKeyBuilder* b) const override;
 
     void onGetBlendInfo(GrXferProcessor::BlendInfo* blendInfo) const override;
 
     bool onIsEqual(const GrXferProcessor& xpBase) const override {
         return true;
     }
 
     typedef GrXferProcessor INHERITED;
 };
@@ skipping 56 matching lines @@
 
 GR_DEFINE_XP_FACTORY_TEST(GrDisableColorXPFactory);
 
 GrXPFactory* GrDisableColorXPFactory::TestCreate(SkRandom* random,
                                                   GrContext*,
                                                   const GrDrawTargetCaps&,
                                                   GrTexture*[]) {
     return GrDisableColorXPFactory::Create();
 }