Create GLSLUniformHandler class for gpu backend

src/gpu/glsl/GrGLSLUniformHandler.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 GrGLSLUniformHandler_DEFINED
+#define GrGLSLUniformHandler_DEFINED
+
+#include "GrGLSLProgramDataManager.h"
+#include "GrGLSLShaderVar.h"
+
+class GrGLSLProgramBuilder;
+
+class GrGLSLUniformHandler {
+public:
+    enum ShaderVisibility {
+        kVertex_Visibility   = 1 << kVertex_GrShaderType,
+        kGeometry_Visibility = 1 << kGeometry_GrShaderType,
+        kFragment_Visibility = 1 << kFragment_GrShaderType,
+    };
+
+    virtual ~GrGLSLUniformHandler() {}
+
+    typedef GrGLSLProgramDataManager::UniformHandle UniformHandle;
+
+    /** Add a uniform variable to the current program, that has visibility in one or more shaders.
+        visibility is a bitfield of ShaderVisibility values indicating from which shaders the
+        uniform should be accessible. At least one bit must be set. Geometry shader uniforms are not
+        supported at this time. The actual uniform name will be mangled. If outName is not nullptr
+        then it will refer to the final uniform name after return. Use the addUniformArray variant
+        to add an array of uniforms. */
+    UniformHandle addUniform(uint32_t visibility,
+                             GrSLType type,
+                             GrSLPrecision precision,
+                             const char* name,
+                             const char** outName = nullptr) {
+        return this->addUniformArray(visibility, type, precision, name, 0, outName);
+    }
+
+    UniformHandle addUniformArray(uint32_t visibility,
+                                  GrSLType type,
+                                  GrSLPrecision precision,
+                                  const char* name,
+                                  int arrayCount,
+                                  const char** outName = nullptr) {
+        return this->internalAddUniformArray(visibility, type, precision, name, true, arrayCount,
+                                             outName);
+    }
+
+    virtual const GrGLSLShaderVar& getUniformVariable(UniformHandle u) const = 0;
+
+    /**
+     * Shortcut for getUniformVariable(u).c_str()
+     */
+    virtual const char* getUniformCStr(UniformHandle u) const = 0;
+protected:
+    explicit GrGLSLUniformHandler(GrGLSLProgramBuilder* program) : fProgramBuilder(program) {}
+
+    // This is not owned by the class
+    GrGLSLProgramBuilder* fProgramBuilder;
+
+private:
+    virtual UniformHandle internalAddUniformArray(uint32_t visibility,
+                                                  GrSLType type,
+                                                  GrSLPrecision precision,
+                                                  const char* name,
+                                                  bool mangleName,
+                                                  int arrayCount,
+                                                  const char** outName) = 0;
+
+    virtual void appendUniformDecls(ShaderVisibility, SkString*) const = 0;
+
+    friend class GrGLSLProgramBuilder;
+};
+
+#endif
+