Add requireHWAA param to GrPipelineBuilder constructor

src/gpu/GrPipelineBuilder.h

Index: src/gpu/GrPipelineBuilder.h
diff --git a/src/gpu/GrPipelineBuilder.h b/src/gpu/GrPipelineBuilder.h
index 08ac5db8b7989bab8de8470e16319af2b8ac7e8f..e1c397f8465b88269c78d50dbe33a5cea4d85f43 100644
--- a/src/gpu/GrPipelineBuilder.h
+++ b/src/gpu/GrPipelineBuilder.h
@@ -35,9 +35,11 @@ public:
      * Initializes the GrPipelineBuilder based on a GrPaint, render target, and clip. Note
      * that GrPipelineBuilder encompasses more than GrPaint. Aspects of GrPipelineBuilder that have
      * no GrPaint equivalents are set to default values with the exception of vertex attribute state
-     * which is unmodified by this function and clipping which will be enabled.
+     * which is unmodified by this function and clipping which will be enabled. HW antialias will
+     * only be enabled if the paint is antialiased and the render target is unified multisampled, or
+     * if requireHWAA is true.
      */
-    GrPipelineBuilder(const GrPaint&, GrRenderTarget*, const GrClip&);

[bsalomon, 2016/04/19 14:57:40]

I'm thinking that the GrPB should completely ignore the GrP's aa setting. GrP's
aa setting really means "should the geometry be antialiased" (I'd consider
taking it off of GrP and making it an explicit param to GrDrawContext's
methods). GrPB's aa setting means "enable msaa". These are only loosely related
and it seems like any inference from GrP's setting to GrPB's setting is better
handled in the geometry-specific rendering code. 

+    GrPipelineBuilder(const GrPaint&, GrRenderTarget*, const GrClip&, bool requireHWAA = false);
 
     virtual ~GrPipelineBuilder();