final KeyguardManager keyguardManager = (KeyguardManager) getSystemService(
        Context.KEYGUARD_SERVICE);
mMtpDisabled = (keyguardManager.isKeyguardLocked() && keyguardManager.isKeyguardSecure()) || !mUnlocked || !isCurrentUser;

+  private final BroadcastReceiver mReceiver = new BroadcastReceiver() {
+    @Override
+    public void onReceive(Context context, Intent intent) {
+      final String action = intent.getAction();
+      if (Intent.ACTION_USER_PRESENT.equals(action)) {
+        // If the media scanner is running, it may currently be calling
+        // sendObjectAdded/Removed, which also synchronizes on mBinder
+        // (and in addition to that, all the native MtpServer methods
+        // lock the same Mutex). If it happens to be in an mtp device
+        // write(), it may block for some time, so process this broadcast
+        // in a thread.
+        new Thread(new Runnable() {
+          @Override
+          public void run() {
+            synchronized (mBinder) {
+              // Unhide the storage units when the user has unlocked the lockscreen
+              if (mMtpDisabled) {
+                addStorageDevicesLocked();
+                mMtpDisabled = false;
+              }
+            }
+          }}, "addStorageDevices").start();
+      }
+    }
+  };