adb_profile_chrome: Use Enter to stop early instead of Ctrl-C

Use Enter to stop early instead of Ctrl-C so that users don't
accidentally hit Ctrl-C during the trace downloading phase.

BUG=337656
NOTRY=true

Review URL: https://codereview.chromium.org/164203004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@251661 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 251661