Files.app: Fixed the problem that dialog opened by Ctrl+O cannot be expand.

To initialize the widget that contains dialog correctly, preferred
size of dialog should be set before.

BUG=238865

Review URL: https://chromiumcodereview.appspot.com/14837004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@199658 0039d316-1c4b-4281-b951-d872f2087c98
3 files changed