Add requireHWAA param to GrPipelineBuilder constructor

src/gpu/GrPipelineBuilder.h

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrPipelineBuilder_DEFINED
 #define GrPipelineBuilder_DEFINED
 
@@ skipping 17 matching lines @@
 class GrTexture;
 
 class GrPipelineBuilder : public SkNoncopyable {
 public:
     GrPipelineBuilder();
 
     /**
      * 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();
 
     ///////////////////////////////////////////////////////////////////////////
     /// @name Fragment Processors
     ///
     /// GrFragmentProcessors are used to compute per-pixel color and per-pixel fractional coverage.
     /// There are two chains of FPs, one for color and one for coverage. The first FP in each
     /// chain gets the initial color/coverage from the GrPrimitiveProcessor. It computes an output
     /// color/coverage which is fed to the next FP in the chain. The last color and coverage FPs
@@ skipping 334 matching lines @@
     mutable SkAutoTUnref<const GrXPFactory> fXPFactory;
     FragmentProcessorArray                  fColorFragmentProcessors;
     FragmentProcessorArray                  fCoverageFragmentProcessors;
     GrClip                                  fClip;
 
     friend class GrPipeline;
     friend class GrDrawTarget;
 };
 
 #endif