[shill] Enable default profile to persist device info

Make Profile::Save() take a pointer to a vector of DeviceRefPtrs.  The base
implementation ignores this pointer, but the DefaultProfile implementation
persists all the devices to disk.

BUG=chromium-os:17254
TEST=unit
STATUS=Verified

Change-Id: I5d72bd2319edfb9ae57366cbd5c766b558ffc8a4
Reviewed-on: http://gerrit.chromium.org/gerrit/8057
Commit-Ready: Chris Masone <cmasone@chromium.org>
Tested-by: Chris Masone <cmasone@chromium.org>
Reviewed-by: Darin Petkov <petkov@chromium.org>
diff --git a/manager.h b/manager.h
index 1104aca..6bddeb5 100644
--- a/manager.h
+++ b/manager.h
@@ -75,6 +75,11 @@
   PropertyStore *mutable_store() { return &store_; }
   virtual const PropertyStore &store() const { return store_; }
 
+  std::vector<DeviceRefPtr>::iterator devices_begin() {
+    return devices_.begin();
+  }
+  std::vector<DeviceRefPtr>::iterator devices_end() { return devices_.end(); }
+
  private:
   friend class ManagerAdaptorInterface;