Fix demuxer_perftest file paths and adjust various perftests' iterations/units.

Several of the benchmarks took too long to run (esp. on android) and so iterations were reduced. Some had too large/small results numbers with 'runs/s', and were switched to 'ms' or 'runs/ms'.

BUG=310837

Review URL: https://codereview.chromium.org/70833002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@234791 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 234791
Blink roll 161853:161871

http://build.chromium.org/f/chromium/perf/dashboard/ui/changelog_blink.html?url=/trunk&range=161854:161871&mode=html
TBR=
BUG=

Review URL: https://codereview.chromium.org/68183012

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@234792 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 234792