GitLab

The site settings page in browser settings was using one method from
each of two otherwise OS-settings-only proxies:
- getAndroidSmsInfo from MultideviceBrowserProxy
- requestAndroidAppsInfo from AndroidAppsBrowserProxy

This CL
- Copies these two methods to a new browser proxy for browser settings
- Removes all usage of the Multidevice and AndroidApps proxies in
browser settings
- Moves the leftover multidevice_page files to the
chromeos/multidevice_page directory
- Removes the multidevice_page/ directory, since this only existed to
hold the proxy and the constants it used.

Bug: 986596
Change-Id: Ia80ccd555fe391b6eea2e02faca1102c779a2963
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1989934Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Commit-Queue: Rebekah Potter <rbpotter@chromium.org>
Cr-Commit-Position: refs/heads/master@{#729619}