Emulate media encryption, always chmod to unlock.

When FBE emulation is enabled, lock/unlock the media directories that
store emulated SD card contents.

Change unlocking logic to always chmod directories back to known
state so that we can recover devices that have disabled FBE
emulation.

Bug: 26010607, 26027473
Change-Id: I6d4bff25d8ad7b948679290106f585f777f7a249
diff --git a/Utils.cpp b/Utils.cpp
index 5276bba..aba3a53 100644
--- a/Utils.cpp
+++ b/Utils.cpp
@@ -576,6 +576,12 @@
     }
 }
 
+std::string BuildDataMediaPath(const char* volumeUuid, userid_t userId) {
+    // TODO: unify with installd path generation logic
+    std::string data(BuildDataPath(volumeUuid));
+    return StringPrintf("%s/media/%u", data.c_str(), userId);
+}
+
 std::string BuildDataUserPath(const char* volumeUuid, userid_t userId) {
     // TODO: unify with installd path generation logic
     std::string data(BuildDataPath(volumeUuid));