GitLab

Refcount an extension so that it if it happens to be reloaded while the dialog
is showing, we don't crash.

BUG=487161
TBR=sky@chromium.org (small extension_uninstall_dialog_view.cc changes, reviewed by kalman)

Review URL: https://codereview.chromium.org/1140053004

Cr-Commit-Position: refs/heads/master@{#330143}