dev: add --attach to make it unnecessary to look up pids

TEST=used --attach with browser and filename on device and VM

Change-Id: I6ab66825386217b406c340c40010849e80b7e2ab
Reviewed-on: https://gerrit.chromium.org/gerrit/11970
Commit-Ready: Ken Mixter <[email protected]>
Tested-by: Ken Mixter <[email protected]>
Reviewed-by: Caroline Tice <[email protected]>
Reviewed-by: asharif <[email protected]>
1 file changed