added support for PLS path rendering

src/gpu/glsl/GrGLSLXferProcessor.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 GrGLSLXferProcessor_DEFINED
 #define GrGLSLXferProcessor_DEFINED
 
@@ skipping 14 matching lines @@
     typedef GrGLSLTextureSampler::TextureSamplerArray TextureSamplerArray;
     struct EmitArgs {
         EmitArgs(GrGLSLXPFragmentBuilder* fragBuilder,
                  GrGLSLUniformHandler* uniformHandler,
                  const GrGLSLCaps* caps,
                  const GrXferProcessor& xp,
                  const char* inputColor,
                  const char* inputCoverage,
                  const char* outputPrimary,
                  const char* outputSecondary,
-                 const TextureSamplerArray& samplers)
+                 const TextureSamplerArray& samplers,
+                 const bool usePLSDstRead)
             : fXPFragBuilder(fragBuilder)
             , fUniformHandler(uniformHandler)
             , fGLSLCaps(caps)
             , fXP(xp)
             , fInputColor(inputColor)
             , fInputCoverage(inputCoverage)
             , fOutputPrimary(outputPrimary)
             , fOutputSecondary(outputSecondary)
-            , fSamplers(samplers) {}
+            , fSamplers(samplers)
+            , fUsePLSDstRead(usePLSDstRead) {}
 
         GrGLSLXPFragmentBuilder* fXPFragBuilder;
         GrGLSLUniformHandler* fUniformHandler;
         const GrGLSLCaps* fGLSLCaps;
         const GrXferProcessor& fXP;
         const char* fInputColor;
         const char* fInputCoverage;
         const char* fOutputPrimary;
         const char* fOutputSecondary;
         const TextureSamplerArray& fSamplers;
+        bool fUsePLSDstRead;
     };
     /**
      * This is similar to emitCode() in the base class, except it takes a full shader builder.
      * This allows the effect subclass to emit vertex code.
      */
     void emitCode(const EmitArgs&);
 
     /** A GrGLSLXferProcessor instance can be reused with any GrGLSLXferProcessor that produces
         the same stage key; this function reads data from a GrGLSLXferProcessor and uploads any
         uniform variables required  by the shaders created in emitCode(). The GrXferProcessor
@@ skipping 36 matching lines @@
                                          const GrXferProcessor&) {
         SkFAIL("emitBlendCodeForDstRead not implemented.");
     }
 
     virtual void onSetData(const GrGLSLProgramDataManager&, const GrXferProcessor&) = 0;
 
     GrGLSLProgramDataManager::UniformHandle fDstTopLeftUni;
     GrGLSLProgramDataManager::UniformHandle fDstScaleUni;
 };
 #endif