bufferpool2.0: add invalidation observer

Change-Id: Idf5cf48865d9b7b831c2890e9652774482af90b8
diff --git a/media/bufferpool/2.0/Accessor.cpp b/media/bufferpool/2.0/Accessor.cpp
index b9837f7..3eaea7c 100644
--- a/media/bufferpool/2.0/Accessor.cpp
+++ b/media/bufferpool/2.0/Accessor.cpp
@@ -114,7 +114,10 @@
 }
 
 // Methods from ::android::hardware::media::bufferpool::V2_0::IAccessor follow.
-Return<void> Accessor::connect(connect_cb _hidl_cb) {
+Return<void> Accessor::connect(
+        const sp<::android::hardware::media::bufferpool::V2_0::IObserver>& observer,
+        connect_cb _hidl_cb) {
+    (void)observer;
     sp<Connection> connection;
     ConnectionId connectionId;
     const StatusDescriptor* fmqDesc;