During upgrade to the Chromium 61 we have switched from GTK2 to GTK3
and now we have a few warnings about stuff being deprecated in GTK3.
Check any Linux build to get a list of them.

/cc @zcbenz 
atom/browser/ui/message_box_gtk.cc
#include "atom/browser/ui/message_box.h"
#include "atom/browser/browser.h"
#include "atom/browser/native_window_observer.h"
#include "atom/browser/native_window_views.h"
#include "atom/browser/unresponsive_suppressor.h"
#include "base/callback.h"
#include "base/strings/string_util.h"
#include "base/strings/utf_string_conversions.h"
#include "chrome/browser/ui/libgtkui/gtk_signal.h"
#include "chrome/browser/ui/libgtkui/gtk_util.h"
#include "chrome/browser/ui/libgtkui/skia_utils_gtk.h"
#include "ui/views/widget/desktop_aura/x11_desktop_handler.h"
#define ANSI_FOREGROUND_RED   "\x1b[31m"
#define ANSI_FOREGROUND_BLACK "\x1b[30m"
#define ANSI_TEXT_BOLD        "\x1b[1m"
#define ANSI_BACKGROUND_GRAY  "\x1b[47m"
#define ANSI_RESET            "\x1b[0m"
namespace atom {
namespace {
class GtkMessageBox : public NativeWindowObserver {