GrFP can express distance vector field req., program builder declares variable for it

src/gpu/glsl/GrGLSLPrimitiveProcessor.h

Index: src/gpu/glsl/GrGLSLPrimitiveProcessor.h
diff --git a/src/gpu/glsl/GrGLSLPrimitiveProcessor.h b/src/gpu/glsl/GrGLSLPrimitiveProcessor.h
index d7260276867aa7f474d1f3c5c364158e4a1a55b4..a94099656b9286468ba51fb950d5af2b29f24c7d 100644
--- a/src/gpu/glsl/GrGLSLPrimitiveProcessor.h
+++ b/src/gpu/glsl/GrGLSLPrimitiveProcessor.h
@@ -42,6 +42,7 @@ public:
                  const GrPrimitiveProcessor& gp,
                  const char* outputColor,
                  const char* outputCoverage,
+                 const char* distanceVectorName,
                  const SamplerHandle* texSamplers,
                  const SamplerHandle* bufferSamplers,
                  const TransformsIn& transformsIn,
@@ -54,6 +55,7 @@ public:
             , fGP(gp)
             , fOutputColor(outputColor)
             , fOutputCoverage(outputCoverage)
+            , fDistanceVectorName(distanceVectorName)
             , fTexSamplers(texSamplers)
             , fBufferSamplers(bufferSamplers)
             , fTransformsIn(transformsIn)
@@ -66,6 +68,7 @@ public:
         const GrPrimitiveProcessor& fGP;
         const char* fOutputColor;
         const char* fOutputCoverage;
+        const char* fDistanceVectorName;
         const SamplerHandle* fTexSamplers;
         const SamplerHandle* fBufferSamplers;
         const TransformsIn& fTransformsIn;
@@ -78,7 +81,6 @@ public:
      */
     virtual void emitCode(EmitArgs&) = 0;
 
-
     /** A GrGLSLPrimitiveProcessor instance can be reused with any GrGLSLPrimitiveProcessor that
         produces the same stage key; this function reads data from a GrGLSLPrimitiveProcessor and
         uploads any uniform variables required  by the shaders created in emitCode(). The