shill: Add Profile and Manager UpdateDevice support.

UpdateDevice persists Devices into profiles. It's similar to UpdateService,
however, only the topmost DefaultProfile handles UpdateDevice. Use UpdateDevice
to persist Device's Enabled and Cellular's AllowRoaming properties. Remove now
unused Manager::SaveActiveProfile method to avoid confusion.

BUG=chrome-os-partner:10178,chromium-os:32230
TEST=unit tests

Change-Id: I1d293fa84e0bce3156943e8e9d313fc98facbde1
Reviewed-on: https://gerrit.chromium.org/gerrit/26405
Tested-by: Darin Petkov <petkov@chromium.org>
Reviewed-by: Paul Stewart <pstew@chromium.org>
Reviewed-by: Ben Chan <benchan@chromium.org>
Commit-Ready: Ben Chan <benchan@chromium.org>
diff --git a/profile.cc b/profile.cc
index 46d589d..6fbb21f 100644
--- a/profile.cc
+++ b/profile.cc
@@ -1,4 +1,4 @@
-// Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
+// Copyright (c) 2012 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.
 
@@ -280,6 +280,10 @@
   return service_groups;
 }
 
+bool Profile::UpdateDevice(const DeviceRefPtr &device) {
+  return false;
+}
+
 void Profile::HelpRegisterDerivedStrings(
     const string &name,
     Strings(Profile::*get)(Error *),