Files.app: Show error messages for the case the source file is not exists.

Previously the error message is shown in a dialog box, but it was broken and
currently there are no errors. The CLs shows the error message in the progress
center.

BUG=341400
TEST=manually

Review URL: https://codereview.chromium.org/163083002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@251782 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 251782