Remove stl_util's STLDeleteContainerPairSecondPointers from chromeos.

BUG=555865

Review-Url: https://codereview.chromium.org/2349593005
Cr-Commit-Position: refs/heads/master@{#419794}
diff --git a/chromeos/network/shill_property_handler.h b/chromeos/network/shill_property_handler.h
index 2fb49d0..fd299b5 100644
--- a/chromeos/network/shill_property_handler.h
+++ b/chromeos/network/shill_property_handler.h
@@ -43,7 +43,7 @@
     : public ShillPropertyChangedObserver,
       public base::SupportsWeakPtr<ShillPropertyHandler> {
  public:
-  typedef std::map<std::string, ShillPropertyObserver*>
+  typedef std::map<std::string, std::unique_ptr<ShillPropertyObserver>>
       ShillPropertyObserverMap;
 
   class CHROMEOS_EXPORT Listener {