Revert of Deletes mojo::Callback

device/serial/serial_connection.h

Index: device/serial/serial_connection.h
diff --git a/device/serial/serial_connection.h b/device/serial/serial_connection.h
index a0e2a80171767a2ddaea482a2afb9f9fdafab483..32c2ca2b1cbe9b15d194a9f074fb33920341f1ee 100644
--- a/device/serial/serial_connection.h
+++ b/device/serial/serial_connection.h
@@ -32,13 +32,16 @@
   ~SerialConnection() override;
 
   // serial::Connection overrides.
-  void GetInfo(const GetInfoCallback& callback) override;
+  void GetInfo(
+      const mojo::Callback<void(serial::ConnectionInfoPtr)>& callback) override;
   void SetOptions(serial::ConnectionOptionsPtr options,
-                  const SetOptionsCallback& callback) override;
+                  const mojo::Callback<void(bool)>& callback) override;
   void SetControlSignals(serial::HostControlSignalsPtr signals,
-                         const SetControlSignalsCallback& callback) override;
-  void GetControlSignals(const GetControlSignalsCallback& callback) override;
-  void Flush(const FlushCallback& callback) override;
+                         const mojo::Callback<void(bool)>& callback) override;
+  void GetControlSignals(
+      const mojo::Callback<void(serial::DeviceControlSignalsPtr)>& callback)
+      override;
+  void Flush(const mojo::Callback<void(bool)>& callback) override;
 
  private:
   void OnSendPipeReady(std::unique_ptr<ReadOnlyBuffer> buffer);