Enable blend optimizations with instanced draws

src/gpu/instanced/GLInstancedRendering.h

Index: src/gpu/instanced/GLInstancedRendering.h
diff --git a/src/gpu/instanced/GLInstancedRendering.h b/src/gpu/instanced/GLInstancedRendering.h
new file mode 100644
index 0000000000000000000000000000000000000000..569e6e316014b5597d0705f42e7feaa4966477ef
--- /dev/null
+++ b/src/gpu/instanced/GLInstancedRendering.h
@@ -0,0 +1,60 @@
+/*
+ * 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 gr_instanced_GLInstancedRendering_DEFINED
+#define gr_instanced_GLInstancedRendering_DEFINED
+
+#include "gl/GrGLBuffer.h"
+#include "instanced/InstancedRendering.h"
+
+class GrGLGpu;
+
+#define GR_GL_LOG_INSTANCED_BATCHES 0
+
+namespace gr_instanced {
+
+class GLInstancedRendering final : public InstancedRendering {
+public:
+    static GLInstancedRendering* CreateIfSupported(GrGLGpu*);
+    ~GLInstancedRendering() override;
+
+private:
+    GLInstancedRendering(GrGLGpu*, AntialiasMode lastSupportedAAMode);
+
+    GrGLGpu* glGpu() const;
+
+    Batch* createBatch() override;
+
+    void onBeginFlush(GrResourceProvider*) override;
+    void onDraw(const GrPipeline&, const InstanceProcessor&, const Batch*) override;
+    void onEndFlush() override;
+    void onResetGpuResources(ResetType) override;
+
+    void flushInstanceAttribs(int baseInstance);
+
+    struct GLDrawCmdInfo {
+        int fInstanceCount;
+#if GR_GL_LOG_INSTANCED_BATCHES
+        IndexRange fGeometry;
+#endif
+    };
+
+    GrGLuint                              fVertexArrayID;
+    SkAutoTUnref<GrGLBuffer>              fInstanceBuffer;
+    SkAutoTUnref<GrGLBuffer>              fDrawIndirectBuffer;
+    SkAutoSTMalloc<1024, GLDrawCmdInfo>   fGLDrawCmdsInfo;
+    uint32_t                              fInstanceAttribsBufferUniqueId;
+    int                                   fInstanceAttribsBaseInstance;
+
+    class GLBatch;
+
+    typedef InstancedRendering INHERITED;
+};
+
+}
+
+#endif