2 files changed, 18 insertions, 1 deletions
diff --git a/device/hid/hid_service.cc b/device/hid/hid_service.cc
index fc50a41..1993999 100644
--- a/device/hid/hid_service.cc
+++ b/device/hid/hid_service.cc
@@ -34,6 +34,10 @@ void HidService::Observer::OnDeviceRemoved(
     scoped_refptr<HidDeviceInfo> device_info) {
 }
 
+void HidService::Observer::OnDeviceRemovedCleanup(
+    scoped_refptr<HidDeviceInfo> device_info) {
+}
+
 HidService* HidService::GetInstance(
     scoped_refptr<base::SingleThreadTaskRunner> file_task_runner) {
   if (g_service == NULL) {
@@ -124,10 +128,15 @@ void HidService::RemoveDevice(const HidDeviceId& device_id) {
   if (it != devices_.end()) {
     HID_LOG(USER) << "HID device removed: deviceId='" << device_id << "'";
 
+    scoped_refptr<HidDeviceInfo> device = it->second;
     if (enumeration_ready_) {
-      FOR_EACH_OBSERVER(Observer, observer_list_, OnDeviceRemoved(it->second));
+      FOR_EACH_OBSERVER(Observer, observer_list_, OnDeviceRemoved(device));
     }
     devices_.erase(it);
+    if (enumeration_ready_) {
+      FOR_EACH_OBSERVER(Observer, observer_list_,
+                        OnDeviceRemovedCleanup(device));
+    }
   }
 }
 
diff --git a/device/hid/hid_service.h b/device/hid/hid_service.h
index 6d6ef2b..4a4d3ad 100644
--- a/device/hid/hid_service.h
+++ b/device/hid/hid_service.h
@@ -27,7 +27,15 @@ class HidService {
   class Observer {
    public:
     virtual void OnDeviceAdded(scoped_refptr<HidDeviceInfo> info);
+    // Notifies all observers that a device is being removed, called before
+    // removing the device from HidService. Observers should not depend on the
+    // order in which they are notified of the OnDeviceRemove event.
     virtual void OnDeviceRemoved(scoped_refptr<HidDeviceInfo> info);
+    // Notifies all observers again, after having first notified all observers
+    // with OnDeviceRemoved and removed the device from internal structures.
+    // Each observer must not depend on any other observers' awareness of the
+    // device as they could be cleaned up in any order.
+    virtual void OnDeviceRemovedCleanup(scoped_refptr<HidDeviceInfo> info);
   };
 
   typedef base::Callback<void(const std::vector<scoped_refptr<HidDeviceInfo>>&)>