shill: Add C++11 override specifier to destructors of derived classes.

BUG=None
TEST=`USE=wimax FEATURES=test emerge-$BOARD platform2`

Change-Id: I88d4e29165869b26924cccb94ac940dc8961c312
Reviewed-on: https://chromium-review.googlesource.com/212267
Reviewed-by: Alex Vakulenko <avakulenko@chromium.org>
Commit-Queue: Ben Chan <benchan@chromium.org>
Tested-by: Ben Chan <benchan@chromium.org>
diff --git a/mock_pending_activation_store.h b/mock_pending_activation_store.h
index 50b5937..f58f1d2 100644
--- a/mock_pending_activation_store.h
+++ b/mock_pending_activation_store.h
@@ -17,7 +17,7 @@
 class MockPendingActivationStore : public PendingActivationStore {
  public:
   MockPendingActivationStore();
-  virtual ~MockPendingActivationStore();
+  ~MockPendingActivationStore() override;
 
   MOCK_METHOD2(InitStorage,
                bool(GLib *glib, const base::FilePath &storage_path));