bluetooth: Clean up WebBluetoothServiceImpl when adapter is removed

content/browser/bluetooth/bluetooth_dispatcher_host.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // ID Not In Map Note:
 // A service, characteristic, or descriptor ID not in the corresponding
 // BluetoothDispatcherHost map [service_to_device_, characteristic_to_service_,
 // descriptor_to_characteristic_] implies a hostile renderer because a renderer
 // obtains the corresponding ID from this class and it will be added to the map
 // at that time.
@@ skipping 465 matching lines @@
     for (device::BluetoothAdapter::Observer* observer : adapter_observers_) {
       adapter_->RemoveObserver(observer);
     }
   }
   adapter_ = adapter;
   if (adapter_.get()) {
     adapter_->AddObserver(this);
     for (device::BluetoothAdapter::Observer* observer : adapter_observers_) {
       adapter_->AddObserver(observer);
     }
+  } else {
+    // Notify that the adapter has been removed and observers should clean up
+    // their state.
+    for (device::BluetoothAdapter::Observer* observer : adapter_observers_) {
+      observer->AdapterPresentChanged(nullptr, false);

[Jeffrey Yasskin, 2016/04/19 21:08:27]

To be strictly correct, this should probably pass the old adapter rather than
nullptr. It's not going to matter any time soon, because we don't deal with
having multiple adapters, but it might matter eventually. 

We should probably send this for every adapter change (with unequal pointers?)
so that notifications never hold dangling references to the old adapter, but I
like your ClearState() implementation, and that only works when changing the
adapter to null, so I endorse limiting the artificial AdapterPresentChange to
this subset of actual changes.

[ortuno, 2016/04/19 21:36:32]

In practice there will never be more than one adapter object, no matter how many
physical adapters the device has (BluetoothAdapter is actually a misnomer. It
doesn't represent a single physical adpater, it manages all adapters and allows
you to access whichever one is available). So this event always called with a
pointer to that adapter object.
Acknowledged.

+    }
   }
 }
 
 void BluetoothDispatcherHost::StartDeviceDiscovery(
     RequestDeviceSession* session,
     int chooser_id) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
   if (session->discovery_session) {
     // Already running; just increase the timeout.
     discovery_session_timer_.Reset();
@@ skipping 916 matching lines @@
     const PrimaryServicesRequest& request) {
   pending_primary_services_requests_[device_address].push_back(request);
 }
 
 url::Origin BluetoothDispatcherHost::GetOrigin(int frame_routing_id) {
   return RenderFrameHostImpl::FromID(render_process_id_, frame_routing_id)
       ->GetLastCommittedOrigin();
 }
 
 }  // namespace content