Use PrintWindow() to implement snapshots on windows 8.1+

ui/snapshot/snapshot_aura.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_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.
+SNAPSHOT_EXPORT bool GrabWindowSnapshotAura(gfx::NativeWindow window,

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

As these functions are only for aura can these take an aura::Window* instead of
gfx::NativeView/Window? Also, can there be just one given NativeView and
NativeWindow are the same for aura?

+                                            const gfx::Rect& snapshot_bounds,

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

Are the bounds in these functions pixels or dips?

+                                            gfx::Image* image);
+
+SNAPSHOT_EXPORT bool GrabViewSnapshotAura(gfx::NativeView view,
+                                          const gfx::Rect& snapshot_bounds,
+                                          gfx::Image* image);
+
+SNAPSHOT_EXPORT void GrabWindowSnapshotAndScaleAsyncAura(
+    gfx::NativeWindow 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(
+    gfx::NativeWindow window,
+    const gfx::Rect& source_rect,
+    const GrabWindowSnapshotAsyncCallback& callback);
+
+SNAPSHOT_EXPORT void GrabViewSnapshotAsyncAura(
+    gfx::NativeView view,
+    const gfx::Rect& source_rect,
+    const GrabWindowSnapshotAsyncCallback& callback);
+
+}  // namespace ui
+
+#endif  // UI_SNAPSHOT_SNAPSHOT_AURA_H_