Fix adding displays in mustash.

Fix adding displays in mustash.

This CL fixes two bugs that occured when adding displays after the
initial display setup.

The first bug is caused by Display::OnViewportMetricsChanged() getting
called before the WindowManagerDisplayRoot for the display is created.
ScreenMus receives a message that a display has been added before the
WindowTreeClient was updated. When ash looked for the root window
controller corresponding to the display it didn't exist yet. Fix by not
calling OnDisplayUpdated() if the ui::ws::Display hasn't been
initialized yet and explicitly call it after WindowManagerDisplayRoot(s)
have been created.

The second bug was not initializing the GPU channel for displays after
the first display.

BUG=641012
Committed: https://crrev.com/ff1f2f190b17b41e787f89f6825d6cc3bbd10bec
Cr-Commit-Position: refs/heads/master@{#418242}

[kylechar, 2016-09-12 17:35:07]

kylechar@chromium.org changed reviewers:
+ msw@chromium.org

[msw, 2016-09-12 17:50:30]

lgtm

[sky, 2016-09-12 20:06:40]

sky@chromium.org changed reviewers:
+ sky@chromium.org

[sky, 2016-09-12 20:06:40]

LGTM

[kylechar, 2016-09-13 13:37:46]

The CQ bit was checked by kylechar@chromium.org

[commit-bot: I haz the power, 2016-09-13 13:38:11]

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, 2016-09-13 14:37:03]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-09-13 14:39:05]

Description was changed from

==========
Fix adding displays in mustash.

This CL fixes two bugs that occured when adding displays after the
initial display setup.

The first bug is caused by Display::OnViewportMetricsChanged() getting
called before the WindowManagerDisplayRoot for the display is created.
ScreenMus receives a message that a display has been added before the
WindowTreeClient was updated. When ash looked for the root window
controller corresponding to the display it didn't exist yet. Fix by not
calling OnDisplayUpdated() if the ui::ws::Display hasn't been
initialized yet and explicitly call it after WindowManagerDisplayRoot(s)
have been created.

The second bug was not initializing the GPU channel for displays after
the first display.

BUG=641012
==========

to

==========
Fix adding displays in mustash.

This CL fixes two bugs that occured when adding displays after the
initial display setup.

The first bug is caused by Display::OnViewportMetricsChanged() getting
called before the WindowManagerDisplayRoot for the display is created.
ScreenMus receives a message that a display has been added before the
WindowTreeClient was updated. When ash looked for the root window
controller corresponding to the display it didn't exist yet. Fix by not
calling OnDisplayUpdated() if the ui::ws::Display hasn't been
initialized yet and explicitly call it after WindowManagerDisplayRoot(s)
have been created.

The second bug was not initializing the GPU channel for displays after
the first display.

BUG=641012

Committed: https://crrev.com/ff1f2f190b17b41e787f89f6825d6cc3bbd10bec
Cr-Commit-Position: refs/heads/master@{#418242}
==========

[commit-bot: I haz the power, 2016-09-13 14:39:06]

Patchset 1 (id:??) landed as
https://crrev.com/ff1f2f190b17b41e787f89f6825d6cc3bbd10bec
Cr-Commit-Position: refs/heads/master@{#418242}