Hide focus ring when ChromeVox is unloaded.

BUG=421422

Review URL: https://codereview.chromium.org/685403004

Cr-Commit-Position: refs/heads/master@{#302131}

chrome/browser/chromeos/accessibility/accessibility_manager.cc

@@ -33,6 +33,7 @@
 #include "chrome/browser/chromeos/login/ui/login_display_host_impl.h"
 #include "chrome/browser/chromeos/login/ui/webui_login_view.h"
 #include "chrome/browser/chromeos/profiles/profile_helper.h"
+#include "chrome/browser/chromeos/ui/accessibility_focus_ring_controller.h"
 #include "chrome/browser/extensions/component_loader.h"
 #include "chrome/browser/extensions/extension_service.h"
 #include "chrome/browser/profiles/profile.h"
@@ -1131,6 +1132,9 @@ void AccessibilityManager::PostUnloadChromeVox(Profile* profile) {
   // Do any teardown work needed immediately after ChromeVox actually unloads.
   if (system_sounds_enabled_)
     ash::PlaySystemSoundAlways(SOUND_SPOKEN_FEEDBACK_DISABLED);
+  // Clear the accessibility focus ring.
+  AccessibilityFocusRingController::GetInstance()->SetFocusRing(
+      std::vector<gfx::Rect>());
 }
 
 }  // namespace chromeos