Remove Windows snapshot code.

ui/snapshot/snapshot_win.h

-// Copyright 2013 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 <vector>
-
-#include "ui/snapshot/snapshot_export.h"
-
-namespace gfx {
-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.
-SNAPSHOT_EXPORT bool GrabHwndSnapshot(
-    HWND window_handle,
-    const gfx::Rect& snapshot_bounds,
-    std::vector<unsigned char>* png_representation);
-
-}  // namespace internal
-}  // namespace ui
-
-#endif  // UI_SNAPSHOT_SNAPSHOT_WIN_H_