[Telemetry]: Support target architectures other than ARM in Telemetry for Android

This change makes Telemetry use locally built android tools  prior to prebuilt ones. This enables Telemetry tests to be run on architectures other than ARM.

The change fixes two issues:
   - CheckForPossibleBrowsers() fail for target architectures other than ARM
   - copy of ARM version of 'purge_ashmem' to the test device no matter device architecture

BUG: None
R: tonyg@chromium.org
TEST: Running Telemetry tests on MIPS Android device
Review URL: https://codereview.chromium.org/167623002/

Review URL: https://codereview.chromium.org/167623002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@254485 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 254485
Resources for the User Manager tutorial

The actual images are still being finalized, so only the 100x versions
are available right now.

BUG=324052
R=oshima@chromium.org

Review URL: https://codereview.chromium.org/176903008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@254486 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 254486