added support for PLS path rendering

src/gpu/GrPrimitiveProcessor.h

Index: src/gpu/GrPrimitiveProcessor.h
diff --git a/src/gpu/GrPrimitiveProcessor.h b/src/gpu/GrPrimitiveProcessor.h
index 467200a86d098316a9226c5c6dcc56db7e14426d..9fc251fe9eb697cbbbed5736a6bdc864e2848d58 100644
--- a/src/gpu/GrPrimitiveProcessor.h
+++ b/src/gpu/GrPrimitiveProcessor.h
@@ -47,6 +47,16 @@ class GrGLSLPrimitiveProcessor;
 
 struct GrInitInvariantOutput;
 
+// Describes the state of pixel local storage with respect to the current draw. 
+enum GrPixelLocalStorageState {
+    // The draw is actively updating PLS.
+    kDraw_State,
+    // The draw is a "finish" operation which is reading from PLS and writing color.
+    kFinish_State,
+    // The draw does not use PLS.
+    kDisabled_State
+};
+
 /*
  * This class allows the GrPipeline to communicate information about the pipeline to a
  * GrBatch which should be forwarded to the GrPrimitiveProcessor(s) created by the batch.
@@ -199,7 +209,7 @@ public:
         the object. */
     virtual GrGLSLPrimitiveProcessor* createGLSLInstance(const GrGLSLCaps& caps) const = 0;
 
-    bool isPathRendering() const { return fIsPathRendering; }
+    virtual bool isPathRendering() const { return false; }
 
     /**
      * No Local Coord Transformation is needed in the shader, instead transformed local coords will
@@ -207,11 +217,12 @@ public:
      */
     virtual bool hasTransformedLocalCoords() const = 0;
 
+    virtual GrPixelLocalStorageState getPixelLocalStorageState() const { return kDisabled_State; }
+    
 protected:
-    GrPrimitiveProcessor(bool isPathRendering)
+    GrPrimitiveProcessor()
         : fNumAttribs(0)
-        , fVertexStride(0)
-        , fIsPathRendering(isPathRendering) {}
+        , fVertexStride(0) {}
 
     Attribute fAttribs[kMaxVertexAttribs];
     int fNumAttribs;
@@ -221,8 +232,6 @@ private:
     void notifyRefCntIsZero() const final {};
     virtual bool hasExplicitLocalCoords() const = 0;
 
-    bool fIsPathRendering;
-
     typedef GrProcessor INHERITED;
 };