keep only one typedef for the native drawing context

skia/ext/native_drawing_context.h

+// Copyright (c) 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef SKIA_EXT_NATIVE_DRAWING_CONTEXT_H_
+#define SKIA_EXT_NATIVE_DRAWING_CONTEXT_H_
+
+#include "build/build_config.h"
+
+#if defined(OS_WIN)
+#include <windows.h>
+#elif defined(USE_CAIRO)
+typedef struct _cairo cairo_t;
+#elif defined(OS_MACOSX)
+typedef struct CGContext* CGContextRef;
+#endif
+
+namespace skia {
+
+#if defined(OS_WIN)
+typedef HDC NativeDrawingContext;
+#elif defined(USE_CAIRO)
+typedef cairo_t* NativeDrawingContext;
+#elif defined(OS_MACOSX)
+typedef CGContextRef NativeDrawingContext;
+#else
+typedef void* NativeDrawingContext;
+#endif
+
+}  // namespace skia
+
+#endif  // SKIA_EXT_NATIVE_DRAWING_CONTEXT_H_