VrShell: Exit fullscreen on app button press.

chrome/browser/android/vr_shell/ui_scene_manager.cc

Index: chrome/browser/android/vr_shell/ui_scene_manager.cc
diff --git a/chrome/browser/android/vr_shell/ui_scene_manager.cc b/chrome/browser/android/vr_shell/ui_scene_manager.cc
index e59a59a32d9bff92d16b95e437a593c2d6dca1e1..4dca2196c94b0a96e53fed98a21751b0c0a55b2a 100644
--- a/chrome/browser/android/vr_shell/ui_scene_manager.cc
+++ b/chrome/browser/android/vr_shell/ui_scene_manager.cc
@@ -223,15 +223,16 @@ void UiSceneManager::SetWebVrSecureOrigin(bool secure) {
 }
 
 void UiSceneManager::OnAppButtonClicked() {
-  // App button click exits the WebVR presentation.
+  // App button click exits the WebVR presentation and fullscreen.
   browser_->ExitPresent();
+  browser_->ExitFullscreen();
 }
 
 void UiSceneManager::OnAppButtonGesturePerformed(
     UiInterface::Direction direction) {}
 
 void UiSceneManager::SetFullscreen(bool fullscreen) {
-  // Make all VR scene UI elements visible if not in WebVR or fullscreen.
+  // Make all VR scene UI elements visible if not in fullscreen.
   for (UiElement* element : browser_ui_elements_) {
     element->set_visible(!fullscreen);
   }