Fix PIP window being blank after minimize/show

DesktopWindowTreeHostX11::SetVisible only made the call into
OnNativeWidgetVisibilityChanged when transitioning from shown
to minimized and not vice versa.  This is because this change
https://chromium-review.googlesource.com/c/chromium/src/+/1437263
considered IsVisible to be true when minimized, which made
IsVisible always true in this case.  This caused layers to be hidden
but never shown again.

Bug: 949199
Change-Id: Ieb31ac5e6856645918aa337f34d47efb947c3910
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1580103
Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: enne <enne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#653890}
4 files changed