Revert of Paint tab-loading throbbers into a ui::Layer.

Revert of Paint tab-loading throbbers into a ui::Layer. (patchset #13 id:270001 of https://codereview.chromium.org/1393193002/ )

Reason for revert:
This is suspected of causing test failures on the Chrome OS trunk build. See crbug.com/546600

Reverting to verify.

Original issue's description:
> Paint tab-loading throbbers into a ui::Layer.
>
> In views browsers, updating the tab loading throbber currently requires
> a repaint that starts at the BrowserView and trickles the damage
> rectangle down until it reaches the favicon area. This uses a lot of CPU
> and energy: about 11 watts above idle on a MacBook Pro (and significant
> CPU on Linux) for a single "waiting" spinner.
>
> Giving the throbber a layer allows the repaint to be isolated, with
> compositing done on the GPU. This brings total energy usage down to
> about 2.5 watts above idle.
>
> Plots at http://crbug.com/391646#c44
>
> BUG=391646
> TEST=Spinners should look and behave the same, but use less energy/CPU.
>
> Committed: https://crrev.com/23f218dbb7d9f4fd2401e71bfa5f23af32d13800
> Cr-Commit-Position: refs/heads/master@{#355514}

TBR=sky@chromium.org,danakj@chromium.org,pkasting@chromium.org,tapted@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=391646
Committed: https://crrev.com/e922e64bebe7f91d89684563c3a99bfbccf6fe7a
Cr-Commit-Position: refs/heads/master@{#355548}

[jonross, 2015-10-22 16:02:17]

Created Revert of Paint tab-loading throbbers into a ui::Layer.

[commit-bot: I haz the power, 2015-10-22 16:02:39]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1415873006/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1415873006/1

[commit-bot: I haz the power, 2015-10-22 16:03:40]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-10-22 16:04:32]

Patchset 1 (id:??) landed as
https://crrev.com/e922e64bebe7f91d89684563c3a99bfbccf6fe7a
Cr-Commit-Position: refs/heads/master@{#355548}