Revert "Make BrowserWithTestWindowTests work with single process Mash"

This reverts commit 01dd4eadad20e021288a3d8db6302fdff024a092.

Reason for revert: Seems to have broken fushcia cast: https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/fuchsia-arm64-cast/2910

Original change's description:
> Make BrowserWithTestWindowTests work with single process Mash
> 
> The InputDeviceClient needs to only be created once, so remove it
> from AuraTestSuiteSetup. Otherwise, in BrowserWithTestWindowTest,
> it gets created twice: during test suite setup, and as part of
> OzonePlatform (due to AshTestHelper/ash::Shell).
> 
> Many tests still need one though, especially those that create a
> WebContents, so add it to RenderViewHostTestEnabler, which should
> take care of all RenderViewHostTestHarness tests or tests that create
> the enabler manually.
> 
> Also update a few other tests to either create their own
> RenderViewHostTestEnabler or InputDeviceClient as appropriate.
> 
> Also the InputDeviceManager can be a true singleton now (not thread-
> singleton).
> 
> Bug: 905430
> Change-Id: I2974968efe0415f0b56218e24b4fa546a1524fe1
> Reviewed-on: https://chromium-review.googlesource.com/c/1341075
> Reviewed-by: Scott Violet <sky@chromium.org>
> Commit-Queue: Evan Stade <estade@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#611556}

TBR=sky@chromium.org,estade@chromium.org

Change-Id: Iadad5f76d31d82e8dc4cd427db184f536fdbef38
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 905430
Reviewed-on: https://chromium-review.googlesource.com/c/1352125
Reviewed-by: Darren Shen <shend@chromium.org>
Commit-Queue: Darren Shen <shend@chromium.org>
Cr-Commit-Position: refs/heads/master@{#611559}
18 files changed