Send vrdisplayactivate to the most recently focused navigator listening for displayactivate.

device/vr/vr_device_manager.cc

Index: device/vr/vr_device_manager.cc
diff --git a/device/vr/vr_device_manager.cc b/device/vr/vr_device_manager.cc
index 249b3c9259ccfa8208f218a67c8a590e83bc5273..994f202f2f05262f0300b981443eb032f1edf6a1 100644
--- a/device/vr/vr_device_manager.cc
+++ b/device/vr/vr_device_manager.cc
@@ -95,7 +95,7 @@ void VRDeviceManager::AddService(VRServiceImpl* service) {
 void VRDeviceManager::RemoveService(VRServiceImpl* service) {
 
   if (service->listening_for_activate()) {
-    ListeningForActivateChanged(false);
+    ListeningForActivateChanged(false, service);
   }
 
   services_.erase(service);
@@ -112,9 +112,14 @@ unsigned int VRDeviceManager::GetNumberOfConnectedDevices() {
   return static_cast<unsigned int>(devices_.size());
 }
 
-void VRDeviceManager::ListeningForActivateChanged(bool listening) {
+void VRDeviceManager::ListeningForActivateChanged(bool listening,
+                                                  VRServiceImpl* service) {
   DCHECK(thread_checker_.CalledOnValidThread());
 
+  if (listening) {
+    most_recently_listening_for_activate_ = service;
+  }
+
   bool activate_listeners = listening;
   if (!activate_listeners) {
     for (auto* service : services_) {
@@ -133,6 +138,13 @@ void VRDeviceManager::ListeningForActivateChanged(bool listening) {
   }
 }
 
+bool VRDeviceManager::IsMostRecentlyListeningForActivate(
+    VRServiceImpl* service) {
+  if (!service)
+    return false;
+  return service == most_recently_listening_for_activate_;
+}
+
 VRDevice* VRDeviceManager::GetDevice(unsigned int index) {
   DCHECK(thread_checker_.CalledOnValidThread());