Refactor how we store and use samplers in Ganesh

src/gpu/gl/GrGLSampler.h

+/*
+* Copyright 2016 Google Inc.
+*
+* Use of this source code is governed by a BSD-style license that can be
+* found in the LICENSE file.
+*/
+
+#ifndef GrGLSampler_DEFINED
+#define GrGLSampler_DEFINED
+
+#include "glsl/GrGLSLSampler.h"
+
+#include "gl/GrGLTypes.h"
+#include "glsl/GrGLSLShaderVar.h"
+
+class GrGLSampler : public GrGLSLSampler {
+public:
+    GrGLSampler(uint32_t visibility,
+                GrPixelConfig config,
+                GrSLType type,
+                GrSLPrecision precision,
+                const char* name) : INHERITED(visibility, config) {
+        SkASSERT(GrSLTypeIsSamplerType(type));
+        fShaderVar.setType(type);
+        fShaderVar.setTypeModifier(GrGLSLShaderVar::kUniform_TypeModifier);
+        fShaderVar.setPrecision(precision);
+        fShaderVar.accessName()->set(name);
+    }
+
+    GrGLint location() const { return fLocation; }
+    GrSLType type() const override { return fShaderVar.getType(); }
+
+    const char* onGetSamplerNameForTexture2D() const override { return fShaderVar.c_str(); }
+    const char* getSamplerNameForTexelFetch() const override { return fShaderVar.c_str(); }
+
+private:
+    GrGLSLShaderVar fShaderVar;
+    GrGLint         fLocation;
+
+    friend class GrGLUniformHandler;
+
+    typedef GrGLSLSampler INHERITED;
+};
+
+#endif