NaCl: FileDownloader now uses FileIO_Private.

This changes the implementation of FileDownloader to use FileIO_Private instead
of FileIOTrusted. This allows us to get rid of the FileIOTrusted interface.

BUG=246396

Review URL: https://codereview.chromium.org/25258004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226677 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 226677
Revert 226618 "Makes RecentlyUsedFoldersComboModel clear interna..."

Results in test failures under asan in linux_chromeos. Verified revert in
a local asan build. It might be the tests that are wrong, but reverting
in case there are more subtle problems not tested.

Problematic tests:
 - unit_tests:BookmarkBubbleViewTest.SyncPromoNotSignedIn
 - unit_tests:BookmarkBubbleViewTest.SyncPromoSignedIn
 - interactive_ui_tests:StarViewTest.HideOnSecondClick

> Makes RecentlyUsedFoldersComboModel clear internal structur when node deleted
> 
> Prior to this RecentlyUsedFoldersComboModel would not clear its
> internal structures if a node was deleted, leading to a future
> crash. This patch makes RecentlyUsedFoldersComboModel clear internal
> structure and notify observers.
> 
> Having the BookmarkModel change while the bubble is showing is rare,
> so the code doesn't attempt to do anything elegant.
> 
> BUG=294330
> TEST=none
> R=msw@chromium.org
> 
> Review URL: https://codereview.chromium.org/25310003

TBR=sky@chromium.org

Review URL: https://codereview.chromium.org/25833002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226678 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 226678