shill: Create mockable ModemManagerProxy on appearance of new ModemManagers.

BUG=chromium-os:17649
TEST=unit tests, tested on device

Change-Id: Id9e6500168d63493eb94bd7939e379b964bef063
Reviewed-on: http://gerrit.chromium.org/gerrit/4269
Tested-by: Darin Petkov <petkov@chromium.org>
Reviewed-by: Chris Masone <cmasone@chromium.org>
diff --git a/modem_manager_proxy_interface.h b/modem_manager_proxy_interface.h
new file mode 100644
index 0000000..e294eea
--- /dev/null
+++ b/modem_manager_proxy_interface.h
@@ -0,0 +1,25 @@
+// Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef SHILL_MODEM_MANAGER_PROXY_INTERFACE_
+#define SHILL_MODEM_MANAGER_PROXY_INTERFACE_
+
+#include <vector>
+
+#include <dbus-c++/types.h>
+
+namespace shill {
+
+// These are the methods that a ModemManager proxy must support. The interface
+// is provided so that it can be mocked in tests.
+class ModemManagerProxyInterface {
+ public:
+  virtual ~ModemManagerProxyInterface() {}
+
+  virtual std::vector<DBus::Path> EnumerateDevices() = 0;
+};
+
+}  // namespace shill
+
+#endif  // SHILL_MODEM_MANAGER_PROXY_INTERFACE_