PM: RealShillProvider should properly cache the connection type.

This exposes (in unit test) and fixes a bug where the RealShillProvider
neglected to update the cached value of the connection type, although it
was marking this value as valid and used it in subsequent calls.

BUG=None
TEST=Unit test added; fails before, passes after.

Change-Id: Ifbb206adcc82706a786ba1828220bb015badbfbc
Reviewed-on: https://chromium-review.googlesource.com/193872
Reviewed-by: Gilad Arnold <garnold@chromium.org>
Tested-by: Gilad Arnold <garnold@chromium.org>
Reviewed-by: Alex Deymo <deymo@chromium.org>
Commit-Queue: Gilad Arnold <garnold@chromium.org>
diff --git a/policy_manager/variable.h b/policy_manager/variable.h
index 2ef0fe1..4507280 100644
--- a/policy_manager/variable.h
+++ b/policy_manager/variable.h
@@ -173,6 +173,7 @@
   FRIEND_TEST(PmRealShillProviderTest, ReadBaseValues);
   FRIEND_TEST(PmRealShillProviderTest, ReadChangedValuesConnectedViaVpn);
   FRIEND_TEST(PmRealShillProviderTest, ReadChangedValuesConnectedTwoSignals);
+  FRIEND_TEST(PmRealShillProviderTest, ConnectionTypeCached);
   FRIEND_TEST(PmRealShillProviderTest, NoInitConnStatusReadBaseValues);
   friend class PmRealTimeProviderTest;
   FRIEND_TEST(PmRealTimeProviderTest, CurrDateValid);