[Win] Don't crash when updating tooltip and the ClientView hasn't been added to the view hierarchy.

ui/views/widget/tooltip_manager_aura.cc

Index: ui/views/widget/tooltip_manager_aura.cc
diff --git a/ui/views/widget/tooltip_manager_aura.cc b/ui/views/widget/tooltip_manager_aura.cc
index 8f22401ea8789c1c1cd5c04c242abae6ddc7387f..1c5bd26c32e600e7e00f7013c15001777c9ce0a6 100644
--- a/ui/views/widget/tooltip_manager_aura.cc
+++ b/ui/views/widget/tooltip_manager_aura.cc
@@ -90,6 +90,10 @@ int TooltipManagerAura::GetMaxWidth(const gfx::Point& point,
 void TooltipManagerAura::UpdateTooltip() {
   aura::Window* root_window = GetWindow()->GetRootWindow();
   if (aura::client::GetTooltipClient(root_window)) {
+    if (!widget_->IsVisible()) {
+      UpdateTooltipForTarget(NULL, gfx::Point(), root_window);
+      return;
+    }
     gfx::Point view_point =
         root_window->GetHost()->dispatcher()->GetLastMouseLocationInRoot();
     aura::Window::ConvertPointToTarget(root_window, GetWindow(), &view_point);