Notify VRDeviceProviders when there are pages listening for vrdisplayactivate

device/vr/vr_device_manager.h

Index: device/vr/vr_device_manager.h
diff --git a/device/vr/vr_device_manager.h b/device/vr/vr_device_manager.h
index 4417470d8fecd9ca06ef708baf9b7e4573c4abf8..f26791708e0d9554111087a1db268802507bf519 100644
--- a/device/vr/vr_device_manager.h
+++ b/device/vr/vr_device_manager.h
@@ -39,6 +39,8 @@ class VRDeviceManager {
   DEVICE_VR_EXPORT bool GetVRDevices(VRServiceImpl* service);
   DEVICE_VR_EXPORT unsigned int GetNumberOfConnectedDevices();
 
+  void ListeningForActivateChanged(bool listening);
+
  private:
   friend class VRDeviceManagerTest;
   friend class VRServiceImplTest;
@@ -77,6 +79,8 @@ class VRDeviceManager {
 
   bool has_scheduled_poll_;
 
+  bool has_activate_listeners_;
+
   base::ThreadChecker thread_checker_;
 
   base::RepeatingTimer timer_;