Revert "Basic Pagination for System Tray"

This reverts commit 323d2978e2da2914026fa8b20df8432e050e1fcb.

Reason for revert: Seems to be causing MSan failures

https://logs.chromium.org/logs/chromium/buildbucket/cr-buildbucket.appspot.com/8913432942427830000/+/steps/ash_unittests/0/logs/Deterministic_failure:_FeaturePodsContainerViewTest.BecomeVisibleInCollapsed__status_CRASH_/0



Original change's description:
> Basic Pagination for System Tray
> 
> Add logic to set FeaturePodsContainer Layout according to page numbers
> Add PageIndicatorView in UnifiedSystemTrayView
> 
> The SystemTray will be limited to show 3x3 FeaturePodButtons at a time.
> Additional Buttons will be added to additional pages.
> The available pages will be signified by small buttons under the
> feature pods container.
> 
> Bug: 914077
> Change-Id: I8e2e1a51b0503bda251e409f7ce77d81f57f136e
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1590610
> Commit-Queue: Ahmed Mehfooz <amehfooz@chromium.org>
> Reviewed-by: Tim Song <tengs@chromium.org>
> Reviewed-by: Jenny Zhang <jennyz@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#659728}

TBR=jennyz@chromium.org,tengs@chromium.org,amehfooz@chromium.org

Change-Id: Icf2ea2aac1812d24e7ca3afbaace985e32e8ab0a
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 914077,963316
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1610676
Reviewed-by: Fergal Daly <fergal@chromium.org>
Commit-Queue: Fergal Daly <fergal@chromium.org>
Cr-Commit-Position: refs/heads/master@{#659825}
6 files changed