Added varying struct

TBR=
BUG=skia:

Committed: https://skia.googlesource.com/skia/+/852ae80b9c3c6fd53f993ac35133d80863993cbe

Review URL: https://codereview.chromium.org/671023002
diff --git a/src/gpu/gl/builders/GrGLFragmentShaderBuilder.h b/src/gpu/gl/builders/GrGLFragmentShaderBuilder.h
index 1637d25..b5f83d4 100644
--- a/src/gpu/gl/builders/GrGLFragmentShaderBuilder.h
+++ b/src/gpu/gl/builders/GrGLFragmentShaderBuilder.h
@@ -10,6 +10,8 @@
 
 #include "GrGLShaderBuilder.h"
 
+class GrGLVarying;
+
 /*
  * This base class encapsulates the functionality which the GP uses to build fragment shaders
  */
@@ -91,6 +93,7 @@
     virtual const char* fragmentPosition() SK_OVERRIDE;
     virtual const char* dstColor() SK_OVERRIDE;
 
+private:
     // Private public interface, used by GrGLProgramBuilder to build a fragment shader
     void emitCodeToReadDstTexture();
     void enableCustomOutput();
@@ -102,14 +105,6 @@
     bool compileAndAttachShaders(GrGLuint programId, SkTDArray<GrGLuint>* shaderIds) const;
     void bindFragmentShaderLocations(GrGLuint programID);
 
-    /*
-     * An internal call for GrGLProgramBuilder to use to add varyings to the vertex shader
-     */
-    void addVarying(GrSLType type,
-                   const char* name,
-                   const char** fsInName,
-                   GrGLShaderVar::Precision fsPrecision = GrGLShaderVar::kDefault_Precision);
-
     // As GLProcessors emit code, there are some conditions we need to verify.  We use the below
     // state to track this.  The reset call is called per processor emitted.
     bool hasReadDstColor() const { return fHasReadDstColor; }
@@ -119,7 +114,11 @@
         fHasReadFragmentPosition = false;
     }
 
-private:
+    /*
+     * An internal call for GrGLProgramBuilder to use to add varyings to the vertex shader
+     */
+    void addVarying(GrGLVarying*, GrGLShaderVar::Precision);
+
     /**
      * Features that should only be enabled by GrGLFragmentShaderBuilder itself.
      */