Fixed crash related to cellular network payment plan retreival.

BUG=chromium-os:8864
TEST=none

Review URL: http://codereview.chromium.org/4690002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@65405 0039d316-1c4b-4281-b951-d872f2087c98
  ~NetworkLibraryImpl() {
    network_manager_observers_.Clear();
    if (network_manager_monitor_)
      DisconnectPropertyChangeMonitor(network_manager_monitor_);
    data_plan_observers_.Clear();
    if (data_plan_monitor_)
      DisconnectDataPlanUpdateMonitor(data_plan_monitor_);
    STLDeleteValues(&network_observers_);
    ClearNetworks();
  }

  ~NetworkLibraryImpl() {
    network_manager_observers_.Clear();
    if (network_manager_monitor_)
      DisconnectPropertyChangeMonitor(network_manager_monitor_);
    data_plan_observers_.Clear();
    if (data_plan_monitor_)
      DisconnectDataPlanUpdateMonitor(data_plan_monitor_);
    STLDeleteValues(&network_observers_);
    ClearNetworks();
  }
