More bluetooth medium code.

internal/platform/implementation/linux/bluetooth_classic_server_socket.h

@@ -0,0 +1,32 @@
+#ifndef PLATFORM_IMPL_LINUX_BLUETOOTH_SERVER_SOCKET_H_
+#define PLATFORM_IMPL_LINUX_BLUETOOTH_SERVER_SOCKET_H_
+
+#include "internal/platform/implementation/bluetooth_classic.h"
+#include "internal/platform/exception.h"
+
+namespace nearby {
+namespace linux {
+class BluetoothServerSocket : api::BluetoothServerSocket {
+public:
+  ~BluetoothServerSocket() = default;
+
+  // https://developer.android.com/reference/android/bluetooth/BluetoothServerSocket.html#accept()
+  //
+  // Blocks until either:
+  // - at least one incoming connection request is available, or
+  // - ServerSocket is closed.
+  // On success, returns connected socket, ready to exchange data.
+  // Returns nullptr on error.
+  // Once error is reported, it is permanent, and ServerSocket has to be
+  // closed.
+  std::unique_ptr<api::BluetoothSocket> Accept() override;
+
+  // https://developer.android.com/reference/android/bluetooth/BluetoothServerSocket.html#close()
+  //
+  // Returns Exception::kIo on error, Exception::kSuccess otherwise.
+  Exception Close() override;
+};
+} // namespace linux
+} // namespace nearby
+
+#endif