Allow ForwardingDelegate to have a null delegate

Allow ForwardingDelegate to have a null delegate

Some ash tests don't have a service_manager::Connector, which means
ForwardingDelegate will end up with a null delegate.

BUG=708287
TEST=none
R=kylechar@chromium.org

[sky, 2017-04-24 16:07:14]

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

[commit-bot: I haz the power, 2017-04-24 16:08:13]

Dry run: 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, 2017-04-24 16:52:38]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2017-04-24 16:52:39]

Dry run: This issue passed the CQ dry run.

[kylechar, 2017-04-24 17:01:21]

Where does ForwardingDisplayDelegate get initialized where there is no delegate
installed?

[sky, 2017-04-24 17:13:32]

On 2017/04/24 17:01:21, kylechar wrote:
> Where does ForwardingDisplayDelegate get initialized where there is no
delegate
> installed?

In hopes of minimizing the number of files in the patch to enable simplified
display management for mushrome I've forked off bits of it (including this).
https://codereview.chromium.org/2833093002/ is the WIP patch with everything. In
that patch ShellPortMash::CreateNativeDisplayDelegate() contains the code to
create NativeDisplayDelegate,
https://codereview.chromium.org/2833093002/diff/40001/ash/mus/bridge/shell_po...
. window_manager_->connector() is null in tests, which means
ForwardingDisplayDelegate will be created with a null delegate.

[kylechar, 2017-04-25 15:43:56]

On 2017/04/24 17:13:32, sky wrote:
> On 2017/04/24 17:01:21, kylechar wrote:
> > Where does ForwardingDisplayDelegate get initialized where there is no
> delegate
> > installed?
> 
> In hopes of minimizing the number of files in the patch to enable simplified
> display management for mushrome I've forked off bits of it (including this).
> https://codereview.chromium.org/2833093002/ is the WIP patch with everything.
In
> that patch ShellPortMash::CreateNativeDisplayDelegate() contains the code to
> create NativeDisplayDelegate,
>
https://codereview.chromium.org/2833093002/diff/40001/ash/mus/bridge/shell_po...
> . window_manager_->connector() is null in tests, which means
> ForwardingDisplayDelegate will be created with a null delegate.

There is supposed to be a guarantee that NDD will run the callbacks. So I think
this added codepath will cause problems with tests if it gets used?
ash_unittests just wouldn't use NDD so it didn't matter.

This change is for ash_mus_unittests right? And does ash_mus_unittests make
calls to ForwardingDisplayDelegate? If so, I think whatever NDD implementation
is used will need to trigger the correct callbacks. ForwardingDisplayDelegate
could be swapped out for FakeDisplayDelegate, or ForwardingDisplayDelegate
should maybe be connected?

[sky, 2017-04-26 22:35:20]

This change is no longer necessary with other changes. So, closing out.