Create GLSLUniformHandler class for gpu backend

src/gpu/glsl/GrGLSLVertexShaderBuilder.h

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrGLSLVertexShader_DEFINED
 #define GrGLSLVertexShader_DEFINED
 
 #include "GrGLSLShaderBuilder.h"
 #include "GrGeometryProcessor.h"
 
 class GrGLSLVarying;
 
+// Enough precision to represent 1 / 2048 accurately in printf
+#define GR_SIGNIFICANT_POW2_DECIMAL_DIG 11
+
 class GrGLSLVertexBuilder : public GrGLSLShaderBuilder {
 public:
     GrGLSLVertexBuilder(GrGLSLProgramBuilder* program);
 
     void transformToNormalizedDeviceSpace(const GrShaderVar& posVar);
 private:
     void onFinalize() override;
     
     const char* fRtAdjustName;
 
     friend class GrGLProgramBuilder;
 
     typedef GrGLSLShaderBuilder INHERITED;
 };
 
 #endif