Replace targetHasUnifiedMultisampling in GrPB constructor

Replaces targetHasUnifiedMultisampling with a simpler "useHWAA". Now
the code that creates a pipeline builder needs to decide on its own
whether it should enable multisampling, rather than relying on the
builder to try and guess.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2041283002

Review-Url: https://codereview.chromium.org/2041283002
diff --git a/src/gpu/batches/GrTessellatingPathRenderer.cpp b/src/gpu/batches/GrTessellatingPathRenderer.cpp
index 6d05250..e9c6e1e 100644
--- a/src/gpu/batches/GrTessellatingPathRenderer.cpp
+++ b/src/gpu/batches/GrTessellatingPathRenderer.cpp
@@ -297,7 +297,7 @@
                                                                   *args.fStyle, *args.fViewMatrix,
                                                                   clipBounds));
 
-    GrPipelineBuilder pipelineBuilder(*args.fPaint, args.fDrawContext->isUnifiedMultisampled());
+    GrPipelineBuilder pipelineBuilder(*args.fPaint, args.fDrawContext->mustUseHWAA(*args.fPaint));
     pipelineBuilder.setUserStencil(args.fUserStencilSettings);
 
     args.fDrawContext->drawBatch(pipelineBuilder, *args.fClip, batch);