Improves focus/activation for aura-mus and DesktopNativeWidgetAura

Improves focus/activation for aura-mus and DesktopNativeWidgetAura

When using DesktopNativeWidgetAura there is a FocusClient per
DesktopNativeWidgetAura. Aura-mus was assuming there would be a global
FocusClient, but that's painful for DesktopNativeWidgetAura. So, this
makes aura-mus work with multiple FocusClients. Specifically this does
the following:

Env gets a function to track the active FocusClient. Env doesn't
maintain this, it's assuming others will. In particular
DesktopWindowTreeHostMus and WindowTreeClient makes call to it.

Focus logic moves out of WindowTreeClient and into
FocusSynchronizer. FocusSynchronizer adds itself as an EnvObserserver
to track when the active FocusClient changes so that it can update the
server.

BUG=660994
TEST=covered by tests
R=ben@chromium.org

Committed: https://crrev.com/3b82d5c5307d2ae7e25243efa006eb13fd631d92
Cr-Commit-Position: refs/heads/master@{#430464}

[sky, 2016-11-07 23:30:40]

The CQ bit was checked by sky@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-11-07 23:31:26]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[Ben Goodger (Google), 2016-11-07 23:33:57]

lgtm

[sky, 2016-11-07 23:35:15]

The CQ bit was checked by sky@chromium.org

[commit-bot: I haz the power, 2016-11-07 23:35:57]

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, 2016-11-08 01:28:41]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-11-08 01:37:59]

Description was changed from

==========
Improves focus/activation for aura-mus and DesktopNativeWidgetAura

When using DesktopNativeWidgetAura there is a FocusClient per
DesktopNativeWidgetAura. Aura-mus was assuming there would be a global
FocusClient, but that's painful for DesktopNativeWidgetAura. So, this
makes aura-mus work with multiple FocusClients. Specifically this does
the following:

Env gets a function to track the active FocusClient. Env doesn't
maintain this, it's assuming others will. In particular
DesktopWindowTreeHostMus and WindowTreeClient makes call to it.

Focus logic moves out of WindowTreeClient and into
FocusSynchronizer. FocusSynchronizer adds itself as an EnvObserserver
to track when the active FocusClient changes so that it can update the
server.

BUG=660994
TEST=covered by tests
R=ben@chromium.org
==========

to

==========
Improves focus/activation for aura-mus and DesktopNativeWidgetAura

When using DesktopNativeWidgetAura there is a FocusClient per
DesktopNativeWidgetAura. Aura-mus was assuming there would be a global
FocusClient, but that's painful for DesktopNativeWidgetAura. So, this
makes aura-mus work with multiple FocusClients. Specifically this does
the following:

Env gets a function to track the active FocusClient. Env doesn't
maintain this, it's assuming others will. In particular
DesktopWindowTreeHostMus and WindowTreeClient makes call to it.

Focus logic moves out of WindowTreeClient and into
FocusSynchronizer. FocusSynchronizer adds itself as an EnvObserserver
to track when the active FocusClient changes so that it can update the
server.

BUG=660994
TEST=covered by tests
R=ben@chromium.org

Committed: https://crrev.com/3b82d5c5307d2ae7e25243efa006eb13fd631d92
Cr-Commit-Position: refs/heads/master@{#430464}
==========

[commit-bot: I haz the power, 2016-11-08 01:38:00]

Patchset 1 (id:??) landed as
https://crrev.com/3b82d5c5307d2ae7e25243efa006eb13fd631d92
Cr-Commit-Position: refs/heads/master@{#430464}

[perkj_chrome, 2016-11-08 09:36:16]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/2480273003/ by perkj@chromium.org.

The reason for reverting is: Seems to cause heap use after free on tests in Mac
Asan 10.9.

https://build.chromium.org/p/chromium.memory/builders/Mac%20ASan%2064%20Tests...

FocusTraversalTest.TraversalWithInvisibleViews
FocusTraversalTest.NormalTraversalMac
FocusTraversalTest.PaneTraversal
FocusTraversalTest.FullKeyboardToggle
FocusTraversalTest.TraversalWithNonEnabledViews
FocusTraversalTest.NormalTraversal
 .