Telemetry: Look for a page's display name when replaying it.

When recording a page, we identify it by its "display name" (name if it has one,
otherwise URL unless it's a file). When replaying a page, however, we always use
its URL to look up the correct WPR file. So pages with names cannot be found.

R=tonyg@chromium.org
BUG=344380

Review URL: https://codereview.chromium.org/169873002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@252052 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 252052