[WIP] Move ownership of PlatformDisplay from ws::Display to ws::WindowServer

Move ownership of PlatformDisplay from ws::Display to ws::WindowServer

In mash mode, an instance of ws::PlatformDisplay used for a drawable
root window is currently owned by ws::Display which means we have to
create a new display for each platform window. This works well for the
"internal window mode" used by Chrome OS (a single drawable surface for
the whole display). However, for "external window mode" (any number of
plaform windows, each with their own drawable surface) the top level
Chrome ServerWindows need to own ws::PlatformDisplay. This CL thus
moves ownership of PlatformDisplay from ws::Display to ws::WindowServer.

BUG=666958

[fwang, 2017-02-07 16:27:27]

fwang@igalia.com changed reviewers:
+ kylechar@chromium.org, tonikitoo@igalia.com

[fwang, 2017-02-07 16:27:27]

I'm not sure we have an agreement on how to implement external window mode
precisely. I'm opening this CL based on
https://codereview.chromium.org/2645093003/#msg15 suggestion. 

This just moves ownership of ws::PlatformDisplay out of ws::Display, but I
suspect this is not enough for external mode. For now, I'm uploading this to
continue the discussion.

[fwang, 2017-02-07 16:27:41]

The CQ bit was checked by fwang@igalia.com to run a CQ dry run

[commit-bot: I haz the power, 2017-02-07 16:27:57]

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, 2017-02-07 17:29:50]

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

[commit-bot: I haz the power, 2017-02-07 17:29:51]

Dry run: This issue passed the CQ dry run.

[fwang, 2017-02-08 13:21:19]

Description was changed from

==========
Move ownership of PlatformDisplay from ws::Display to ws::WindowServer

In mash mode, an instance of ws::PlatformDisplay used for a drawable
root window is currently owned by ws::Display which means we have to
create a new display for each platform window. This works well for the
"internal window mode" used by Chrome OS (a single drawable surface for
the whole display). However, for "external window mode" (any number of
plaform windows, each with their own drawable surface) the top level
Chrome ServerWindows need to own ws::PlatformDisplay. This CL thus
moves ownership of PlatformDisplay from ws::Display to ws::WindowServer.

BUG=None
==========

to

==========
Move ownership of PlatformDisplay from ws::Display to ws::WindowServer

In mash mode, an instance of ws::PlatformDisplay used for a drawable
root window is currently owned by ws::Display which means we have to
create a new display for each platform window. This works well for the
"internal window mode" used by Chrome OS (a single drawable surface for
the whole display). However, for "external window mode" (any number of
plaform windows, each with their own drawable surface) the top level
Chrome ServerWindows need to own ws::PlatformDisplay. This CL thus
moves ownership of PlatformDisplay from ws::Display to ws::WindowServer.

BUG=666958
==========

[kylechar, 2017-02-08 14:28:17]

On 2017/02/07 16:27:27, fwang wrote:
> I'm not sure we have an agreement on how to implement external window mode
> precisely. I'm opening this CL based on
> https://codereview.chromium.org/2645093003/#msg15 suggestion. 
> 
> This just moves ownership of ws::PlatformDisplay out of ws::Display, but I
> suspect this is not enough for external mode. For now, I'm uploading this to
> continue the discussion.

Let me talk with rjkroege to see what I missed from the Ozone wayland meeting at
BlinkOn. I'll see if he's available today.

[kylechar, 2017-02-09 18:03:05]

On 2017/02/08 14:28:17, kylechar wrote:
> On 2017/02/07 16:27:27, fwang wrote:
> > I'm not sure we have an agreement on how to implement external window mode
> > precisely. I'm opening this CL based on
> > https://codereview.chromium.org/2645093003/#msg15 suggestion. 
> > 
> > This just moves ownership of ws::PlatformDisplay out of ws::Display, but I
> > suspect this is not enough for external mode. For now, I'm uploading this to
> > continue the discussion.
> 
> Let me talk with rjkroege to see what I missed from the Ozone wayland meeting
at
> BlinkOn. I'll see if he's available today.

So what I got from talking with rjkroege is that for each ws::Display we have
one top level Chrome window. ws::Display is a bit of misnomer, it's not a
display at all, it's just equivalent to cc::Display which is for a top level
drawable thing.

In that case the relationship still holds that ws::Display =
gfx::AcceleratedWidget so this isn't necessary?

[fwang, 2017-02-16 08:42:00]

Yes, I believe we can just continue to create an ws::Display (maybe renaming it)
for each external window. Closing this.