Merge "Clarifies that filesystem permission 0700 is not enforced as an invariant" into mnc-docs

<ul>

  <li>

    Private files’ file permissions can no longer be relaxed by the owner, and

    an attempt to do so using

    Private files’ file permissions should no longer be relaxed by the owner,

    and an attempt to do so using

    {@link android.content.Context#MODE_WORLD_READABLE} and/or

    {@link android.content.Context#MODE_WORLD_WRITEABLE}, will trigger a

    {@link java.lang.SecurityException}.

    <p class="note">

      <strong>Note:</strong> As of yet, this restriction is not fully enforced.

      Apps may still modify permissions to their private directory using

      native APIs or the {@link java.io.File File} API. However, we strongly

      discourage relaxing the permissions to the private directory.

    </p>

  </li>

  <li>

    Passing <code>file://</code> URIs outside the package domain may leave the