VR: Factor transient timing out of UiSceneManager.

chrome/browser/android/vr_shell/ui_elements/presentation_toast.cc

Index: chrome/browser/android/vr_shell/ui_elements/presentation_toast.cc
diff --git a/chrome/browser/android/vr_shell/ui_elements/presentation_toast.cc b/chrome/browser/android/vr_shell/ui_elements/presentation_toast.cc
index a2b4a87b5c02e1f39bc23b158a34a46c1c41323e..28ef2738a8ba61da3d489928747eea1215c0b81e 100644
--- a/chrome/browser/android/vr_shell/ui_elements/presentation_toast.cc
+++ b/chrome/browser/android/vr_shell/ui_elements/presentation_toast.cc
@@ -9,9 +9,11 @@
 
 namespace vr_shell {
 
-PresentationToast::PresentationToast(int preferred_width)
+PresentationToast::PresentationToast(int preferred_width,
+                                     const base::TimeDelta& timeout)
     : TexturedElement(preferred_width),
-      texture_(base::MakeUnique<PresentationToastTexture>()) {}
+      texture_(base::MakeUnique<PresentationToastTexture>()),
+      transience_(this, base::TimeDelta::FromSeconds(10)) {}
 
 PresentationToast::~PresentationToast() = default;