bluetooth: Remove indicator only when there are no more devices connected

content/browser/bluetooth/bluetooth_dispatcher_host.cc

Index: content/browser/bluetooth/bluetooth_dispatcher_host.cc
diff --git a/content/browser/bluetooth/bluetooth_dispatcher_host.cc b/content/browser/bluetooth/bluetooth_dispatcher_host.cc
index fe6fc27aaa51e0b59d5cc0e3f5e770d60043943a..0752c7cce2f1888426436f5d3b877c4e46f277e6 100644
--- a/content/browser/bluetooth/bluetooth_dispatcher_host.cc
+++ b/content/browser/bluetooth/bluetooth_dispatcher_host.cc
@@ -724,18 +724,19 @@ void BluetoothDispatcherHost::OnGATTServerDisconnect(
     return;
   }
 
-  RenderFrameHostImpl* render_frame_host =
-      RenderFrameHostImpl::FromID(render_process_id_, frame_routing_id);
-  WebContents* web_contents =
-      WebContents::FromRenderFrameHost(render_frame_host);
-  if (web_contents) {
-    web_contents->SetBluetoothDeviceConnected(false);
-  }
-
   // The last BluetoothGattConnection for a device closes the connection when
   // it's destroyed.
   if (device_id_to_connection_map_.erase(device_id)) {
     VLOG(1) << "Disconnecting device: " << device_id;
+
+    // Indicate there is one less connected device.
+    RenderFrameHostImpl* render_frame_host =
+        RenderFrameHostImpl::FromID(render_process_id_, frame_routing_id);
+    WebContents* web_contents =
+        WebContents::FromRenderFrameHost(render_frame_host);
+    if (web_contents) {
+      web_contents->DecrementBluetoothConnectedDeviceCount();

[Jeffrey Yasskin, 2016/03/31 18:00:25]

Are we guaranteed that if a process crashes, it'll disconnect all of its
connections? What if the device goes out of range and the connection is lost?
Can we wind up leaking a connection count here?

[ortuno, 2016/04/04 21:20:56]

From some experimentation it seems that if the RenderProcress crashes, the
RenderProcessHost does not get notified. So we would remain connected until the
RenderProcessHost is destroyed. I hope that by moving to frame an implementing a
WebContentsObserver we can get notified of this.
This is actually not hard to solve. We would just have to keep track of the
frames that have active connections and when a device disconnects notify the
WebContents for that frame.

The part that I can't solve is hiding the indicator when the frame navigates
because we have no way of knowing of navigation events. We could try to
implement WebContentsObserver but I think that time would better spent moving to
frame.

+    }
   }
 }
 
@@ -1461,7 +1462,7 @@ void BluetoothDispatcherHost::OnGATTConnectionCreated(
   WebContents* web_contents =
       WebContents::FromRenderFrameHost(render_frame_host);
   if (web_contents) {
-    web_contents->SetBluetoothDeviceConnected(true);
+    web_contents->IncrementBluetoothConnectedDeviceCount();
   }
   Send(new BluetoothMsg_GATTServerConnectSuccess(thread_id, request_id));
 }