Fix gdb viewg command

While following the steps from
docs/graphical_debugging_aid_chromium_views.md using gdb.

Change-Id: Ic4d2193c29604bc548bdb6c84e8f0f70684366e8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1522560
Reviewed-by: Leonard Grey <lgrey@chromium.org>
Reviewed-by: Jeremy Roman <jbroman@chromium.org>
Reviewed-by: Thomas Anderson <thomasanderson@chromium.org>
Commit-Queue: Thomas Anderson <thomasanderson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#641050}