Wait for the print preview generation in progress before submitting the print job.

BUG=141426

Review URL: https://codereview.chromium.org/179233003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@254346 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 254346