Add a cache to LockPatternUtils

Caches responses from LockSettingsService in the client process.

Bug: 15088101
Change-Id: If77c5ec45f52a02c800d50cb8550bfcb180f301d
diff --git a/Android.mk b/Android.mk
index de93ca2..9c41f9f 100644
--- a/Android.mk
+++ b/Android.mk
@@ -276,6 +276,7 @@
 	core/java/com/android/internal/view/IInputMethodSession.aidl \
 	core/java/com/android/internal/view/IInputSessionCallback.aidl \
 	core/java/com/android/internal/widget/ILockSettings.aidl \
+	core/java/com/android/internal/widget/ILockSettingsObserver.aidl \
 	core/java/com/android/internal/widget/IRemoteViewsFactory.aidl \
 	core/java/com/android/internal/widget/IRemoteViewsAdapterConnection.aidl \
 	keystore/java/android/security/IKeyChainAliasCallback.aidl \