Implement instanced rendering for simple shapes

src/gpu/gl/GrGLInstancedRendering.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 GrGLInstancedRendering_DEFINED
+#define GrGLInstancedRendering_DEFINED
+
+#include "GrInstancedRendering.h"
+#include "gl/GrGLFunctions.h"
+
+class GrGLGpu;
+
+class GrGLInstancedRendering final : public GrInstancedRendering {
+public:
+    static GrGLInstancedRendering* CreateIfSupported(GrGLGpu*);
+    ~GrGLInstancedRendering() override;
+
+private:
+    GrGLInstancedRendering(GrGLGpu*, uint32_t supportedAAModes);
+
+    GrGLGpu* glGpu() const;
+
+    Batch* constructBatch(void* storage, int instanceIdx) override;
+
+    void onBeginFlush(GrResourceProvider*) override;
+    void onDraw(const GrPipeline&, const GrInstanceProcessor&, const Batch*) override;
+    void onEndFlush() override;
+    void onResetGpuResources(ResetType) override;
+
+    void flushAttribArrays();
+
+    GrGLuint                 fVertexArrayID;
+    uint32_t                 fInstanceBufferInVertexArrayID;
+    int                      fTotalDrawCmdCount;
+    SkAutoTUnref<GrBuffer>   fDrawIndirectBuffer;
+
+    class GLBatch;
+
+    typedef GrInstancedRendering INHERITED;
+};
+
+#endif