Tentatively goes into WebVR presentation mode if page listens to vrdisplayactivate.

device/vr/vr_display_impl.cc

Index: device/vr/vr_display_impl.cc
diff --git a/device/vr/vr_display_impl.cc b/device/vr/vr_display_impl.cc
index 46542389da940711da252a54c4d87a4460f8fab2..d564b19de76dc3ef649fcb0ecd3ef676bdfbbb89 100644
--- a/device/vr/vr_display_impl.cc
+++ b/device/vr/vr_display_impl.cc
@@ -45,11 +45,12 @@ void VRDisplayImpl::OnFocus() {
   client_->OnFocus();
 }
 
-void VRDisplayImpl::OnActivate(mojom::VRDisplayEventReason reason) {
+void VRDisplayImpl::OnActivate(mojom::VRDisplayEventReason reason,
+                               const base::Callback<void(bool)>& on_handled) {
   VRDeviceManager* manager = VRDeviceManager::GetInstance();
   if (!manager->IsMostRecentlyListeningForActivate(service_))
     return;
-  client_->OnActivate(reason);
+  client_->OnActivate(reason, on_handled);
 }
 
 void VRDisplayImpl::OnDeactivate(mojom::VRDisplayEventReason reason) {