perf ui browser: Allow initial use without navigation UI elements

perf ui browser: Allow initial use without navigation UI elements

The selection and scroll bar are really needed only when the user starts
navigating, before that it just provide distractions.

This also brings the initial screen to look more like the stdio UI,
which more people are used to.

The new code is flexible enough that menu like browsers can opt out and
start with those UI elements.

Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-jfgok30kkerpfw8wtcltgy6z@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>