Reland: Add code to deal with serial device disconnection detection on Windows

device/serial/serial_io_handler_win.h

Index: device/serial/serial_io_handler_win.h
diff --git a/device/serial/serial_io_handler_win.h b/device/serial/serial_io_handler_win.h
index 7f438b53ae4a83f74252bfe6013407d625da4a76..6c160addefe2d607423b7728837d8ece10c9df1a 100644
--- a/device/serial/serial_io_handler_win.h
+++ b/device/serial/serial_io_handler_win.h
@@ -15,6 +15,9 @@ namespace device {
 
 class SerialIoHandlerWin : public SerialIoHandler,
                            public base::MessageLoopForIO::IOHandler {
+ public:
+  class UiThreadHelper;

[Reilly Grant (use Gerrit), 2015/11/11 20:43:59]

This class should be private.

[juncai, 2015/11/12 05:27:08]

Done.

+
  protected:
   // SerialIoHandler implementation.
   void ReadImpl() override;
@@ -44,6 +47,8 @@ class SerialIoHandlerWin : public SerialIoHandler,
                      DWORD bytes_transfered,
                      DWORD error) override;
 
+  void RemoveDevice(const std::string& device_path);

[Reilly Grant (use Gerrit), 2015/11/11 20:43:59]

s/RemoveDevice/OnDeviceRemoved/

[juncai, 2015/11/12 05:27:08]

Done.

+
   // Context used for asynchronous WaitCommEvent calls.
   scoped_ptr<base::MessageLoopForIO::IOContext> comm_context_;
 
@@ -61,6 +66,11 @@ class SerialIoHandlerWin : public SerialIoHandler,
   // after a corresponding WaitCommEvent has completed.
   bool is_comm_pending_;
 
+  // The helper lives on the UI thread and holds a weak reference back to the
+  // handler that owns it.
+  UiThreadHelper* helper_;
+  base::WeakPtrFactory<SerialIoHandlerWin> weak_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(SerialIoHandlerWin);
 };