aura: Do not show tooltips if mouse cursor is hidden.

ash/tooltips/tooltip_controller.cc

Index: ash/tooltips/tooltip_controller.cc
diff --git a/ash/tooltips/tooltip_controller.cc b/ash/tooltips/tooltip_controller.cc
index d3efc1fe0c0f8ae5e8eebad7adddd0e6cbb9697d..ba69352dd915a60e7ec42f24467d602d8ac8de62 100644
--- a/ash/tooltips/tooltip_controller.cc
+++ b/ash/tooltips/tooltip_controller.cc
@@ -372,7 +372,8 @@ void TooltipController::TooltipTimerFired() {
 }
 
 void TooltipController::UpdateIfRequired() {
-  if (!tooltips_enabled_ || mouse_pressed_ || IsDragDropInProgress()) {
+  if (!tooltips_enabled_ || mouse_pressed_ || IsDragDropInProgress() ||
+      !Shell::GetRootWindow()->cursor_shown()) {
     tooltip_->Hide();
     return;
   }