Revert "wm/views: makes objects using Env take Env"

This reverts commit 9feb99aabc8b58121c23b6edc7c024d5385cc4b7.

Reason for revert: a patch earlier in the chain caused msan failures.

Original change's description:
> wm/views: makes objects using Env take Env
> 
> This allows for multiple Envs at the same time. Additionally:
> . NativeWidgetPrivate::CreateNativeWidget: now takes InitParams
> . NativeWidgetPrivate::IsMouseButtonDown() is now an member function.
> 
> BUG=847992
> TEST=covered by tests
> 
> Change-Id: Ic35b274c0a927a7c602809a7e611383b5d3dd3e2
> Reviewed-on: https://chromium-review.googlesource.com/1166148
> Commit-Queue: Scott Violet <sky@chromium.org>
> Reviewed-by: Michael Wasserman <msw@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#581621}

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

Change-Id: I9410bf471a71d07b32f49a139b7afa9ced0f3fea
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 847992
Reviewed-on: https://chromium-review.googlesource.com/1168403
Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#581716}
20 files changed