skia/ext: do not assume Skia's headers include windows.h

skia/ext/platform_surface.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_PLATFORM_SURFACE_H_
 #define SKIA_EXT_PLATFORM_SURFACE_H_
 
 #include "build/build_config.h"
 
 #include "third_party/skia/include/core/SkTypes.h"
 #include "third_party/skia/include/core/SkRect.h"
 
-#if defined(USE_CAIRO)
+#if defined(OS_WIN)
+#include <windows.h>
+#elif defined(USE_CAIRO)
 typedef struct _cairo cairo_t;
 typedef struct _cairo_rectangle cairo_rectangle_t;
 #elif defined(OS_MACOSX)
 typedef struct CGContext* CGContextRef;
 typedef struct CGRect CGRect;
 #endif
 
 namespace skia {
 
 #if defined(OS_WIN)
 typedef HDC PlatformSurface;
 typedef RECT PlatformRect;
 #elif defined(USE_CAIRO)
 typedef cairo_t* PlatformSurface;
 typedef cairo_rectangle_t PlatformRect;
 #elif defined(OS_MACOSX)
 typedef CGContextRef PlatformSurface;
 typedef CGRect PlatformRect;
 #else
 typedef void* PlatformSurface;
 typedef SkIRect* PlatformRect;
 #endif
 
 }  // namespace skia
 
 #endif  // SKIA_EXT_PLATFORM_SURFACE_H_