Fix WeakPtrFactory ordering problems in src/tools

tools/android/forwarder2/device_controller.h

Index: tools/android/forwarder2/device_controller.h
diff --git a/tools/android/forwarder2/device_controller.h b/tools/android/forwarder2/device_controller.h
index b1441d81a789c18fba3dc22f8a0224859c63f571..567a08d936b695625e95ccf6477bc3edcecbf006 100644
--- a/tools/android/forwarder2/device_controller.h
+++ b/tools/android/forwarder2/device_controller.h
@@ -49,7 +49,6 @@ class DeviceController {
       const base::WeakPtr<DeviceController>& device_controller_ptr,
       scoped_ptr<DeviceListener> device_listener);
 
-  base::WeakPtrFactory<DeviceController> weak_ptr_factory_;
   const scoped_ptr<Socket> host_socket_;
   // Used to notify the controller to exit.
   const int exit_notifier_fd_;
@@ -58,6 +57,12 @@ class DeviceController {
   const scoped_refptr<base::SingleThreadTaskRunner> construction_task_runner_;
   ListenersMap listeners_;
 
+  //WeakPtrFactory's documentation says:
+  // Member variables should appear before the WeakPtrFactory, to ensure
+  // that any WeakPtrs to Controller are invalidated before its members
+  // variable's destructors are executed, rendering them invalid.
+  base::WeakPtrFactory<DeviceController> weak_ptr_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(DeviceController);
 };