Remove hasMixedSamples() from GrPipelineBuilder

tools/debugger/SkOverdrawMode.cpp

Index: tools/debugger/SkOverdrawMode.cpp
diff --git a/tools/debugger/SkOverdrawMode.cpp b/tools/debugger/SkOverdrawMode.cpp
index 1e018babdbd40944b021aecd8e60747505b2c6dd..bbf61cc76b2dd545f0a2e1d117e71d73c8322921 100644
--- a/tools/debugger/SkOverdrawMode.cpp
+++ b/tools/debugger/SkOverdrawMode.cpp
@@ -229,9 +229,7 @@ private:
         return new OverdrawXP(dstTexture, hasMixedSamples);
     }
 
-    bool onWillReadDstColor(const GrCaps& caps,
-                            const GrPipelineOptimizations& optimizations,
-                            bool hasMixedSamples) const override {
+    bool onWillReadDstColor(const GrCaps&, const GrPipelineOptimizations&) const override {
         return true;
     }