Stop chromevox audio and clear focus highlight on switch to arc app

ash/ash_touch_exploration_manager_chromeos.cc

Index: ash/ash_touch_exploration_manager_chromeos.cc
diff --git a/ash/ash_touch_exploration_manager_chromeos.cc b/ash/ash_touch_exploration_manager_chromeos.cc
index 058553043f958349afe4d30cf0027243aa344ea8..68aba77b51297ebdc0e0d4ba7b74b408e8c05046 100644
--- a/ash/ash_touch_exploration_manager_chromeos.cc
+++ b/ash/ash_touch_exploration_manager_chromeos.cc
@@ -121,6 +121,10 @@ void AshTouchExplorationManager::UpdateTouchExplorationState() {
         root_window_controller_->GetRootWindow(), this));
   } else if (!spoken_feedback_enabled || pass_through_surface) {
     touch_exploration_controller_.reset();
+    if (spoken_feedback_enabled) {
+      SilenceSpokenFeedback();
+      WmShell::Get()->accessibility_delegate()->ClearFocusHighlight();
+    }
   }
 }