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

This reverts commit 07aab203cab863a00744ef6598091dde9741ba17.

Reason for revert: msan issue was fixed and landed (and wasn't triggered by this patch). Reverting the revert to reland.

Original change's description:
> 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}

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

Change-Id: I1fcd75fb66d00693dfc2e0b78e871848a335319a
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 847992
Reviewed-on: https://chromium-review.googlesource.com/1168566
Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#581797}
20 files changed