Refactor ShelfTooltipManager

This CL moves ShelfTooltipManager from ShelfView to Shelf.

Bug: 997807
Change-Id: I407d17fabdcbb84957074c88014caa0e3214de7e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1776938
Commit-Queue: Andrew Xu <andrewxu@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Reviewed-by: Manu Cornet <manucornet@chromium.org>
Cr-Commit-Position: refs/heads/master@{#695893}
10 files changed