Use PrintWindow() to implement snapshots on windows 8.1+

ui/snapshot/snapshot_aura.h

Index: ui/snapshot/snapshot_aura.h
diff --git a/ui/snapshot/snapshot_aura.h b/ui/snapshot/snapshot_aura.h
new file mode 100644
index 0000000000000000000000000000000000000000..425dcf6c363224df3128272cf9eef8f2be234fa4
--- /dev/null
+++ b/ui/snapshot/snapshot_aura.h
@@ -0,0 +1,30 @@
+// 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_AURA_H_
+#define UI_SNAPSHOT_SNAPSHOT_AURA_H_
+
+#include "ui/snapshot/snapshot.h"
+
+namespace ui {
+
+// These functions are identical to those in snapshot.h, except they're
+// guaranteed to read the frame using an Aura CopyOutputRequest and not the
+// native windowing system. source_rect and target_size are in DIP.
+
+SNAPSHOT_EXPORT void GrabWindowSnapshotAndScaleAsyncAura(
+    aura::Window* window,
+    const gfx::Rect& source_rect,
+    const gfx::Size& target_size,
+    scoped_refptr<base::TaskRunner> background_task_runner,
+    const GrabWindowSnapshotAsyncCallback& callback);
+
+SNAPSHOT_EXPORT void GrabWindowSnapshotAsyncAura(
+    aura::Window* window,
+    const gfx::Rect& source_rect,
+    const GrabWindowSnapshotAsyncCallback& callback);
+
+}  // namespace ui
+
+#endif  // UI_SNAPSHOT_SNAPSHOT_AURA_H_