AU: Don't use network on expensive connection types

Specifically:

- FlimFlam proxy class to query the current network status and find
out if it's expensive.
- Dbus Interface, so dbus can be mocked.
- Libcurl change to redirect the URL if we are on an expensive
connection. This may seem hacky, but the reason I avoided retooling
the whole class is that we may decide that some network usage is
okay on pricy connections. Perhaps it's okay to throttle. So, for
now this is a more minimal change.

BUG=chromium-os:2397
TEST=Unit tests, tested that flimflam proxy works on the device.

Review URL: http://codereview.chromium.org/4029002

Change-Id: Ic4dcde1ca863bda890bc46a55c552e2b32d9433d
diff --git a/mock_dbus_interface.h b/mock_dbus_interface.h
new file mode 100644
index 0000000..bf0d609
--- /dev/null
+++ b/mock_dbus_interface.h
@@ -0,0 +1,37 @@
+// Copyright (c) 2010 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 CHROMEOS_PLATFORM_UPDATE_ENGINE_MOCK_DBUS_INTERFACE_H__
+#define CHROMEOS_PLATFORM_UPDATE_ENGINE_MOCK_DBUS_INTERFACE_H__
+
+#include <gmock/gmock.h>
+
+#include "update_engine/dbus_interface.h"
+
+namespace chromeos_update_engine {
+
+class MockDbusGlib : public DbusGlibInterface {
+ public:
+  MOCK_METHOD5(ProxyNewForNameOwner, DBusGProxy*(DBusGConnection *connection,
+                                                 const char *name,
+                                                 const char *path,
+                                                 const char *interface,
+                                                 GError **error));
+
+  MOCK_METHOD1(ProxyUnref, void(DBusGProxy* proxy));
+
+  MOCK_METHOD2(BusGet, DBusGConnection*(DBusBusType type, GError **error));
+
+  MOCK_METHOD7(ProxyCall, gboolean(DBusGProxy *proxy,
+                                   const char *method,
+                                   GError **error,
+                                   GType first_arg_type,
+                                   GType var_arg1,
+                                   GHashTable** var_arg2,
+                                   GType var_arg3));
+};
+
+}  // namespace chromeos_update_engine
+
+#endif  // CHROMEOS_PLATFORM_UPDATE_ENGINE_MOCK_DBUS_INTERFACE_H__