Implement support for mixed sampled render targets

src/gpu/GrPipeline.cpp

Index: src/gpu/GrPipeline.cpp
diff --git a/src/gpu/GrPipeline.cpp b/src/gpu/GrPipeline.cpp
index fc9f4eab12ecb1b4171bed990eca4f73841f0f10..b1fffe2065e36e7b66f999cbd57f52fc32dcc794 100644
--- a/src/gpu/GrPipeline.cpp
+++ b/src/gpu/GrPipeline.cpp
@@ -33,7 +33,16 @@ GrPipeline::GrPipeline(const GrPipelineBuilder& pipelineBuilder,
     if (xferProcessor) {
         fXferProcessor.reset(xferProcessor.get());
 
-        optFlags = xferProcessor->getOptimizations(colorPOI,
+        GrProcOptInfo localColorPOI = colorPOI;
+        // Optimizations will try to turn off blending which is required by mixed
+        // sampled modes.
+        SkASSERT(pipelineBuilder.fRenderTarget.get());
+        bool isMixedSampledTarget = pipelineBuilder.fRenderTarget.get()->sampleConfig() ==
+                                    GrRenderTarget::kStencil_SampleConfig;
+        localColorPOI.setHasMixedSamplesModulation(pipelineBuilder.isHWAntialias() &&
+                                                   isMixedSampledTarget);
+
+        optFlags = xferProcessor->getOptimizations(localColorPOI,
                                                    coveragePOI,
                                                    pipelineBuilder.getStencil().doesWrite(),
                                                    &overrideColor,