VR: Factor transient timing out of UiSceneManager.

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

Index: chrome/browser/android/vr_shell/ui_elements/presentation_toast.h
diff --git a/chrome/browser/android/vr_shell/ui_elements/presentation_toast.h b/chrome/browser/android/vr_shell/ui_elements/presentation_toast.h
index f131798bf31c26d734366773fa12f4dc12c796c0..729d15eb279048440d9c3e91df9706fec2806b88 100644
--- a/chrome/browser/android/vr_shell/ui_elements/presentation_toast.h
+++ b/chrome/browser/android/vr_shell/ui_elements/presentation_toast.h
@@ -9,6 +9,7 @@
 
 #include "base/macros.h"
 #include "chrome/browser/android/vr_shell/ui_elements/textured_element.h"
+#include "chrome/browser/android/vr_shell/ui_elements/transience_manager.h"
 
 namespace vr_shell {
 
@@ -18,13 +19,18 @@ class UiTexture;
 // insecure_content_transient_texture. Consider refactor(see crbug.com/735166).
 class PresentationToast : public TexturedElement {
  public:
-  explicit PresentationToast(int preferred_width);
+  PresentationToast(int preferred_width, const base::TimeDelta& timeout);
   ~PresentationToast() override;
+  TransienceManager* transience() { return &transience_; }
+
+  // This element manages its own visibility.
+  void SetEnabled(bool enabled) override;
 
  private:
   UiTexture* GetTexture() const override;
 
   std::unique_ptr<UiTexture> texture_;
+  TransienceManager transience_;
 
   DISALLOW_COPY_AND_ASSIGN(PresentationToast);
 };