[Dice] Add drop down button to signin button in user menu

The "Sync to another account" button in the user menu
is removed and instead a drop down button is added to
the right of the sign-in button.

Bug: 824546
Change-Id: I8b1b892962b17229dfdc057169a7f18132ffb58b
Reviewed-on: https://chromium-review.googlesource.com/1133978
Reviewed-by: Elly Fong-Jones <ellyjones@chromium.org>
Commit-Queue: Thomas Tangl <tangltom@chromium.org>
Cr-Commit-Position: refs/heads/master@{#574548}
1 file changed