Revert 239784 "Make page_cycler.py fully measure memory for each..."

> Make page_cycler.py fully measure memory for each page.
> 
> Telemetry makes the distinction between metrics collected for each page and for
> each page set. The fine-grained memory metrics were collected only per page set
> (although there was some histogram data collected per page).
> 
> This CL makes the memory metric module systematically report the whole data per
> page (and not only per page set) so that we can measure pages independently.
> The per page set memory metric collection is now a no-op.
> 
> BUG=323494
> 
> Review URL: https://codereview.chromium.org/91573003

TBR=pliard@chromium.org

Review URL: https://codereview.chromium.org/111773002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@239791 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 239791