Create new tab-loading animation

This implements three parts of the new tab-loading animation:

* Bottom bouncing pill of the indeterminate waiting state.
* Painting the loading state.
* Fading out the loading state animation once progress hits 100%.

This also makes all BrowserView tab animations' indeterminate state run
off of the same timer so this animation stays in sync across multiple
tabs. This timer restarts every time the animation timer starts, so the
first visible animation starts at 0 but following ones use the same
elapsed time as the already-running one.

Bug: chromium:822067
Change-Id: I7f5c38a92dc26556d11a01765831497027913f38
Reviewed-on: https://chromium-review.googlesource.com/c/1060605
Commit-Queue: Peter Boström <pbos@chromium.org>
Reviewed-by: Bret Sepulveda <bsep@chromium.org>
Reviewed-by: Michael Wasserman <msw@chromium.org>
Reviewed-by: Charlie Reis <creis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#604356}
23 files changed