Fix surface crash.

Fix surface crash.

When the surface app is asked to destroy the surface associated with the
current display, it didn't notify the display, which will crash if the
display schedules a draw before being reassociated with a surface. This
fixes this by resetting the display that it isn't associated with a
surface anymore.

R=jamesr@chromium.org

Committed: https://chromium.googlesource.com/external/mojo/+/bd5de96d715d4d2ade0696c8fccc699bbd766d52

[qsr, 2015-02-12 16:11:42]

James, can you confirm this is the right fix.

Otherwise, what should I be doing? Right now, this is crashing a lot on android
where this will happen when you rotate your phone (and also of course, when you
go in the background when fixing the fact that we do not update the context),
but I guess this can happen with a very bad timing when you resize your screen
on Linux too.

[qsr, 2015-02-12 16:42:13]

Hum, just notifying the display doesn't work when the context is then changed,
because the display has a reference to the GL context, so change the CL to reset
the display and rebuilding it.

[jamesr, 2015-02-12 18:27:22]

This seems fine.  We really should have mojom interface for manipulating the
Display as an object but we don't need that today.

[jamesr, 2015-02-12 18:33:58]

lgtm

[qsr, 2015-02-13 14:23:13]

Committed patchset #2 (id:20001) manually as
bd5de96d715d4d2ade0696c8fccc699bbd766d52 (presubmit successful).