Make GrDashEffect take a AA mode enum.

src/gpu/batches/GrDashLinePathRenderer.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrDashLinePathRenderer.h"
 
 #include "GrGpu.h"
 #include "GrAuditTrail.h"
 #include "effects/GrDashingEffect.h"
 
 bool GrDashLinePathRenderer::onCanDrawPath(const CanDrawPathArgs& args) const {
     SkPoint pts[2];
     if (args.fStyle->isDashed() && args.fPath->isLine(pts)) {
         return GrDashingEffect::CanDrawDashLine(pts, *args.fStyle, *args.fViewMatrix);
     }
     return false;
 }
 
 bool GrDashLinePathRenderer::onDrawPath(const DrawPathArgs& args) {
     GR_AUDIT_TRAIL_AUTO_FRAME(args.fDrawContext->auditTrail(),
                               "GrDashLinePathRenderer::onDrawPath");
     bool msaaIsEnabled = args.fDrawContext->isUnifiedMultisampled();
+    GrDashingEffect::AAMode aaMode;
+    if (msaaIsEnabled) {
+        // We ignore args.fAntiAlias here and force anti aliasing when using MSAA. Otherwise,
+        // we can wind up with external edges antialiased and internal edges unantialiased.
+        aaMode = GrDashingEffect::AAMode::kCoverageWithMSAA;
+    } else if (args.fAntiAlias) {
+        aaMode = GrDashingEffect::AAMode::kCoverage;
+    } else {
+        aaMode = GrDashingEffect::AAMode::kNone;
+    }
     SkPoint pts[2];
     SkAssertResult(args.fPath->isLine(pts));
     SkAutoTUnref<GrDrawBatch> batch(GrDashingEffect::CreateDashLineBatch(args.fColor,
                                                                          *args.fViewMatrix,
                                                                          pts,
-                                                                         args.fAntiAlias,
-                                                                         msaaIsEnabled,
+                                                                         aaMode,
                                                                          *args.fStyle));
     if (!batch) {
         return false;
     }
 
     GrPipelineBuilder pipelineBuilder(*args.fPaint, msaaIsEnabled);

[csmartdalton, 2016/06/07 15:04:32]

Just an FYI-- The patch doesn't introduce a change in functionality that I can
see, but until
https://codereview.chromium.org/2041283002/, that second parameter to the
constructor is just one element to GrPB's formula about whether it should enable
hwaa.

So for now we are still getting into a weird, half AA half non-AA state when
support to disable MSAA exists. Because the PB will disable HWAA when
paint.isAntiAlias() is false.

[bsalomon, 2016/06/07 15:11:58]

But that'll be fixed with your upcoming change right?

     pipelineBuilder.setUserStencil(args.fUserStencilSettings);
 
     args.fDrawContext->drawBatch(pipelineBuilder, *args.fClip, batch);
     return true;
 }