Create GLSLUniformHandler class for gpu backend

src/gpu/glsl/GrGLSLProgramBuilder.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "glsl/GrGLSLProgramBuilder.h"
 
 const int GrGLSLProgramBuilder::kVarsPerBlock = 8;
@@ skipping 16 matching lines @@
         if (out->endsWith('_')) {
             // Names containing "__" are reserved.
             out->append("x");
         }
         out->appendf("_Stage%d%s", fStageIndex, fFS.getMangleString().c_str());
     }
 }
 
 void GrGLSLProgramBuilder::appendUniformDecls(ShaderVisibility visibility,
                                               SkString* out) const {
-    this->onAppendUniformDecls(visibility, out);
+    this->uniformHandler()->appendUniformDecls(visibility, out);
 }