[Merge to M59] Gtk3: Add background class to tooltips

[Merge to M59] Gtk3: Add background class to tooltips

> This CL fixes the tooltip background color on the non-Dark variant of
> Adwaita which requires tooltips have the "background" class [1].
>
> Additionally, this CL avoids creating a selector with a GtkWindow
> parent class on Gtk 3.20.  This avoids tinting the tooltip with the
> window background color if tooltips have transparency (FYI: Chrome
> tooltips are opaque, so the alpha will be ignored).
>
> [1] https://github.com/GNOME/gtk/blob/ee3994f715a2f53519f1478d2f08c6548471a8ae/gtk/theme/Adwaita/gtk-contained.css#L4387
>
> BUG=716599
> R=erg@chromium.org
>
> Review-Url: https://codereview.chromium.org/2855063002
> Cr-Commit-Position: refs/heads/master@{#469165}

BUG=716599
TBR=erg@chromium.org
NOTRY=true
NOPRESUBMIT=true

Review-Url: https://codereview.chromium.org/2863843002
Cr-Commit-Position: refs/branch-heads/3071@{#410}
Cr-Branched-From: a106f0abbf69dad349d4aaf4bcc4f5d376dd2377-refs/heads/master@{#464641}
Committed: https://chromium.googlesource.com/chromium/src/+/f750c37727efbda389408dc93b81c8861cacae5d

[Tom (Use chromium acct), 2017-05-04 23:47:30]

The CQ bit was checked by thomasanderson@google.com

[commit-bot: I haz the power, 2017-05-04 23:48:24]

CQ is trying da patch.

Follow status at:
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-05-04 23:49:23]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1493941650000340, "parent_rev":
"a8a34ad21983863dcfd0554e6b129257d936e1d4", "commit_rev":
"f750c37727efbda389408dc93b81c8861cacae5d"}

[commit-bot: I haz the power, 2017-05-04 23:49:57]

Description was changed from

==========
[Merge to M59] Gtk3: Add background class to tooltips

> This CL fixes the tooltip background color on the non-Dark variant of
> Adwaita which requires tooltips have the "background" class [1].
>
> Additionally, this CL avoids creating a selector with a GtkWindow
> parent class on Gtk 3.20.  This avoids tinting the tooltip with the
> window background color if tooltips have transparency (FYI: Chrome
> tooltips are opaque, so the alpha will be ignored).
>
> [1]
https://github.com/GNOME/gtk/blob/ee3994f715a2f53519f1478d2f08c6548471a8ae/gt...
>
> BUG=716599
> R=erg@chromium.org
>
> Review-Url: https://codereview.chromium.org/2855063002
> Cr-Commit-Position: refs/heads/master@{#469165}

BUG=716599
TBR=erg@chromium.org
NOTRY=true
NOPRESUBMIT=true
==========

to

==========
[Merge to M59] Gtk3: Add background class to tooltips

> This CL fixes the tooltip background color on the non-Dark variant of
> Adwaita which requires tooltips have the "background" class [1].
>
> Additionally, this CL avoids creating a selector with a GtkWindow
> parent class on Gtk 3.20.  This avoids tinting the tooltip with the
> window background color if tooltips have transparency (FYI: Chrome
> tooltips are opaque, so the alpha will be ignored).
>
> [1]
https://github.com/GNOME/gtk/blob/ee3994f715a2f53519f1478d2f08c6548471a8ae/gt...
>
> BUG=716599
> R=erg@chromium.org
>
> Review-Url: https://codereview.chromium.org/2855063002
> Cr-Commit-Position: refs/heads/master@{#469165}

BUG=716599
TBR=erg@chromium.org
NOTRY=true
NOPRESUBMIT=true

Review-Url: https://codereview.chromium.org/2863843002
Cr-Commit-Position: refs/branch-heads/3071@{#410}
Cr-Branched-From:
a106f0abbf69dad349d4aaf4bcc4f5d376dd2377-refs/heads/master@{#464641}
Committed:
https://chromium.googlesource.com/chromium/src/+/f750c37727efbda389408dc93b81...
==========

[commit-bot: I haz the power, 2017-05-04 23:49:58]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/f750c37727efbda389408dc93b81...