bufferpool2.0: Implement buffer invalidation

Change-Id: If7a4a38004f50b4d43a2fae4781f541fe322c249
diff --git a/media/bufferpool/2.0/Connection.cpp b/media/bufferpool/2.0/Connection.cpp
index cd837a1..6bd0e79 100644
--- a/media/bufferpool/2.0/Connection.cpp
+++ b/media/bufferpool/2.0/Connection.cpp
@@ -60,6 +60,13 @@
     }
 }
 
+ResultStatus Connection::flush() {
+    if (mInitialized && mAccessor) {
+        return mAccessor->flush();
+    }
+    return ResultStatus::CRITICAL_ERROR;
+}
+
 ResultStatus Connection::allocate(
         const std::vector<uint8_t> &params, BufferId *bufferId,
         const native_handle_t **handle) {