telemetry: Fix screen recording with multiple connected devices

Make it possible to use the Android screen recording profiler with
multiple connected devices. Only the screen on the device that is
actually running the telemetry test will get recorded.

BUG=331435
TEST=tools/perf/run_benchmark smoothness.key_mobile_sites \
--page-filter=linus --browser=android-content-shell \
--profiler=android-screen-recorder
NOTRY=true

Review URL: https://codereview.chromium.org/119323008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@243080 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 243080