Revert "telemetry: Add GetRendererProcessFromTab to timeline model."

This reverts commit r233417.  The change was causing all smoothness tests to
timeout on the perf waterfall.

BUG=316178
TBR=tonyg@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/60103008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@233614 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 233614