Android: Init SelectPopup from native

SelectPopup is the only object invoked from native before Java
side initialization is performed, which led to adding a call in
|WebContentsImpl.initialize| to trigger the init operation. This
CL removes the explicit init by having native do it in a lazy
manner before invoking Java side |show|.

Bug: 868238
Change-Id: I8691607472bd8432f4ff3379b9e1452bb76ca21c
Reviewed-on: https://chromium-review.googlesource.com/1155270
Commit-Queue: Jinsuk Kim <jinsukkim@chromium.org>
Reviewed-by: Bo <boliu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#579325}
6 files changed