Implement permission_broker for serial devices.

device/serial/serial_io_handler.h

Index: device/serial/serial_io_handler.h
diff --git a/device/serial/serial_io_handler.h b/device/serial/serial_io_handler.h
index 5b2d0592db6983e52e65c67014fb01cf81d91ab7..9ceb884b2569f4839f81f342e086427815f4e38d 100644
--- a/device/serial/serial_io_handler.h
+++ b/device/serial/serial_io_handler.h
@@ -32,6 +32,9 @@ class SerialIoHandler : public base::NonThreadSafe,
   virtual void Open(const std::string& port,
                     const OpenCompleteCallback& callback);
 
+  // TODO: Comment.
+  void OnRequestAccessComplete(const std::string& port, bool success);
+
   // Performs an async Read operation. Behavior is undefined if this is called
   // while a Read is already pending. Otherwise, the Done or DoneWithError
   // method on |buffer| will eventually be called with a result.
@@ -102,6 +105,11 @@ class SerialIoHandler : public base::NonThreadSafe,
   // Platform-specific write cancelation.
   virtual void CancelWriteImpl() = 0;
 
+  // TODO: Comment.
+  virtual void RequestAccess(
+      const std::string& port,
+      scoped_refptr<base::MessageLoopProxy> io_message_loop);
+
   // Performs platform-specific, one-time port configuration on open.
   virtual bool PostOpen();