Re-land:

chrome/browser/chromeos/login/screen_locker.cc

Index: chrome/browser/chromeos/login/screen_locker.cc
===================================================================
--- chrome/browser/chromeos/login/screen_locker.cc	(revision 85284)
+++ chrome/browser/chromeos/login/screen_locker.cc	(working copy)
@@ -198,7 +198,9 @@
 // focus/events inside the grab widget.
 class LockWindow : public views::WidgetGtk {
  public:
-  LockWindow() : toplevel_focus_widget_(NULL) {
+  LockWindow()
+      : views::WidgetGtk(new views::Widget),
+        toplevel_focus_widget_(NULL) {
     EnableDoubleBuffer(true);
   }
 
@@ -289,7 +291,8 @@
 class GrabWidget : public views::WidgetGtk {
  public:
   explicit GrabWidget(chromeos::ScreenLocker* screen_locker)
-      : screen_locker_(screen_locker),
+      : views::WidgetGtk(new views::Widget),
+        screen_locker_(screen_locker),
         ALLOW_THIS_IN_INITIALIZER_LIST(task_factory_(this)),
         grab_failure_count_(0),
         kbd_grab_status_(GDK_GRAB_INVALID_TIME),
@@ -730,9 +733,10 @@
   gfx::Rect init_bounds(views::Screen::GetMonitorAreaNearestPoint(left_top));
 
   LockWindow* lock_window = new LockWindow();
-  lock_window_ = lock_window;
+  lock_window_ = lock_window->GetWidget();
   views::Widget::InitParams params(views::Widget::InitParams::TYPE_WINDOW);
   params.bounds = init_bounds;
+  params.native_widget = lock_window;
   lock_window_->Init(params);
   gtk_widget_modify_bg(
       lock_window_->GetNativeView(), GTK_STATE_NORMAL, &kGdkBlack);
@@ -755,12 +759,13 @@
   // TryGrabAllInputs() method later.  (Nobody else needs to use it, so moving
   // its declaration to the header instead of keeping it in an anonymous
   // namespace feels a bit ugly.)
-  GrabWidget* cast_lock_widget = new GrabWidget(this);
-  lock_widget_ = cast_lock_widget;
+  GrabWidget* grab_widget = new GrabWidget(this);
+  lock_widget_ = grab_widget->GetWidget();
   views::Widget::InitParams lock_params(
       views::Widget::InitParams::TYPE_CONTROL);
   lock_params.transparent = true;
   lock_params.parent_widget = lock_window_;
+  lock_params.native_widget = grab_widget;
   lock_widget_->Init(lock_params);
   if (screen_lock_view_) {
     GrabWidgetRootView* root_view = new GrabWidgetRootView(screen_lock_view_);
@@ -790,11 +795,11 @@
   lock_window_->SetContentsView(background_view_);
   lock_window_->Show();
 
-  cast_lock_widget->ClearGtkGrab();
+  grab_widget->ClearGtkGrab();
 
   // Call this after lock_window_->Show(); otherwise the 1st invocation
   // of gdk_xxx_grab() will always fail.
-  cast_lock_widget->TryGrabAllInputs();
+  grab_widget->TryGrabAllInputs();
 
   // Add the window to its own group so that its grab won't be stolen if
   // gtk_grab_add() gets called on behalf on a non-screen-locker widget (e.g.