Use PrintWindow() to implement snapshots on windows 8.1+

ui/snapshot/snapshot_win.h

+// Copyright 2017 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 UI_SNAPSHOT_SNAPSHOT_WIN_H_
+#define UI_SNAPSHOT_SNAPSHOT_WIN_H_
+
+#include <windows.h>
+
+#include "ui/snapshot/snapshot_export.h"
+
+namespace gfx {
+class Image;
+class Rect;
+}
+
+namespace ui {
+namespace internal {
+
+// Grabs a snapshot of the desktop. No security checks are done.  This is
+// intended to be used for debugging purposes where no BrowserProcess instance
+// is available (ie. tests). DO NOT use in a result of user action.

[sky, 2017/03/23 03:29:13]

Can you put this file in a target that is not part of snapshot and is internal
for tests and the snapshot target? If you do that gn check should fail if
someone tries to use this outside of that environment.

+// snapshot_bounds is the area relative to clip_rect that should be captured.
+// Areas outside clip_rect are filled white. clip_rect is relative to the
+// client area of the window, and snapshot_bounds is relative to the
+// clip_rect.
+SNAPSHOT_EXPORT bool GrabHwndSnapshot(HWND window_handle,
+                                      const gfx::Rect& snapshot_bounds,
+                                      const gfx::Rect& clip_rect,
+                                      gfx::Image* image);
+
+}  // namespace internal
+}  // namespace ui
+
+#endif  // UI_SNAPSHOT_SNAPSHOT_WIN_H_