bluetooth: Shutdown BluetoothAdapter before DBus on ChromeOS.

device/bluetooth/bluetooth_adapter_chromeos.h

Index: device/bluetooth/bluetooth_adapter_chromeos.h
diff --git a/device/bluetooth/bluetooth_adapter_chromeos.h b/device/bluetooth/bluetooth_adapter_chromeos.h
index eda84cb42d3412203891b8b559c5e2ac0c49cd18..af466f2509f0045430ce29ad623c21ef3d403258 100644
--- a/device/bluetooth/bluetooth_adapter_chromeos.h
+++ b/device/bluetooth/bluetooth_adapter_chromeos.h
@@ -47,6 +47,7 @@ class DEVICE_BLUETOOTH_EXPORT BluetoothAdapterChromeOS
   static base::WeakPtr<BluetoothAdapter> CreateAdapter();
 
   // BluetoothAdapter:
+  void Shutdown();
   void DeleteOnCorrectThread() const override;
   void AddObserver(device::BluetoothAdapter::Observer* observer) override;
   void RemoveObserver(device::BluetoothAdapter::Observer* observer) override;
@@ -240,6 +241,9 @@ class DEVICE_BLUETOOTH_EXPORT BluetoothAdapterChromeOS
   // ended (with either success or failure).
   void ProcessQueuedDiscoveryRequests();
 
+  // Set in |Shutdown()|, makes IsPresent()| return false.
+  bool dbus_is_shutdown_;
+
   // Number of discovery sessions that have been added.
   int num_discovery_sessions_;