Fixes bug that could lead to wrong deletion in maps

ViewManager server could end up removing from internal map when it
shouldn't have. It should only update view_map_ if the view is from
the current connection.

Really the map should be in terms of ViewId. I'll look into that
separately.

R=erg@chromium.org, msw@chromium.org

Review URL: https://codereview.chromium.org/719813003