GitLab

This CL includes the following refactorings:
- minimized home is simply a layer instead of views
- moves the mouse click handler of minimized home to home card impl
- home card now has the same size of the screen. Changing state is
  now simply changing its position.

Then schedule the animation between BOTTOM state and CENTERED state.

BUG=398062
R=sadrul@chromium.org, oshima@chromium.org
TEST=manually on remote desktop

Review URL: https://codereview.chromium.org/478293004

Cr-Commit-Position: refs/heads/master@{#292092}