Extract AppFuse as a util

Bug: 110379912
Test: testOpenProxyFileDescriptor
Change-Id: I0429a498d7b54682efe9b05815f3470e8745609e
diff --git a/AppFuseUtil.h b/AppFuseUtil.h
new file mode 100644
index 0000000..463c6d0
--- /dev/null
+++ b/AppFuseUtil.h
@@ -0,0 +1,36 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ANDROID_VOLD_APP_FUSE_UTIL_H_
+#define ANDROID_VOLD_APP_FUSE_UTIL_H_
+
+#include <android-base/unique_fd.h>
+
+#define DEBUG_APPFUSE 0
+
+namespace android {
+namespace vold {
+
+int MountAppFuse(uid_t uid, int mountId, android::base::unique_fd* device_fd);
+
+int UnmountAppFuse(uid_t uid, int mountId);
+
+int OpenAppFuseFile(uid_t uid, int mountId, int fileId, int flags);
+
+}  // namespace vold
+}  // namespace android
+
+#endif  // ANDROID_VOLD_APP_FUSE_UTIL_H_