Hookup the page-indicator and progress-bar elements in the PDF extension.

This hooks up the page-indicator (so that the correct page is displayed) and
the progress bar (so that the correct progress is displayed) in PDF.

BUG=303491
R=arv@chromium.org, koz@chromium.org

Review URL: https://codereview.chromium.org/138703009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@252175 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 252175