Create GLSLUniformHandler class for gpu backend

src/gpu/gl/GrGLUniformHandler.h

+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef GrGLUniformHandler_DEFINED
+#define GrGLUniformHandler_DEFINED
+
+#include "glsl/GrGLSLUniformHandler.h"
+
+#include "gl/GrGLProgramDataManager.h"
+
+class GrGLCaps;
+
+static const int kUniformsPerBlock = 8;
+
+class GrGLUniformHandler : public GrGLSLUniformHandler {
+public:
+    const GrGLSLShaderVar& getUniformVariable(UniformHandle u) const override {
+        return fUniforms[u.toIndex()].fVariable;
+    }
+
+    const char* getUniformCStr(UniformHandle u) const override {
+        return this->getUniformVariable(u).c_str();
+    }
+private:
+    explicit GrGLUniformHandler(GrGLSLProgramBuilder* program)
+        : INHERITED(program)
+        , fUniforms(kUniformsPerBlock) {}
+
+    UniformHandle internalAddUniformArray(uint32_t visibility,
+                                          GrSLType type,
+                                          GrSLPrecision precision,
+                                          const char* name,
+                                          bool mangleName,
+                                          int arrayCount,
+                                          const char** outName) override;
+
+    void appendUniformDecls(ShaderVisibility, SkString*) const override;
+
+    // Manually set uniform locations for all our uniforms.
+    void bindUniformLocations(GrGLuint programID, const GrGLCaps& caps);
+
+    // Updates the loction of the Uniforms if we cannot bind uniform locations manually
+    void getUniformLocations(GrGLuint programID, const GrGLCaps& caps);
+
+    const GrGLGpu* glGpu() const;
+
+    typedef GrGLProgramDataManager::UniformInfo UniformInfo;
+    typedef GrGLProgramDataManager::UniformInfoArray UniformInfoArray;
+
+    UniformInfoArray fUniforms;
+
+    friend class GrGLProgramBuilder;
+
+    typedef GrGLSLUniformHandler INHERITED; 
+};
+
+#endif