Add mixed samples support to XPs

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 187 matching lines @@
      */
     GrRenderTarget* getRenderTarget() const { return fRenderTarget.get(); }
 
     /**
      * Sets the render-target used at the next drawing call
      *
      * @param target  The render target to set.
      */
     void setRenderTarget(GrRenderTarget* target) { fRenderTarget.reset(SkSafeRef(target)); }
 
+    /**
+     * Returns whether the rasterizer and stencil test (if any) will run at a higher sample rate
+     * than the color buffer. In is scenario, the higher sample rate is resolved during blending.
+     */
+    bool hasMixedSamples() const {
+        return this->isHWAntialias() && !fRenderTarget->isMultisampled();
+    }
+
     /// @}
 
     ///////////////////////////////////////////////////////////////////////////
     /// @name Stencil
     ////
 
     const GrStencilSettings& getStencil() const { return fStencilSettings; }
 
     /**
      * Sets the stencil settings to use for the next draw.
@@ skipping 218 matching lines @@
     mutable GrProcOptInfo fCoverageProcInfo;
     mutable bool fColorProcInfoValid;
     mutable bool fCoverageProcInfoValid;
     mutable GrColor fColorCache;
     mutable GrColor fCoverageCache;
 
     friend class GrPipeline;
 };
 
 #endif