Ozone integration.

Ozone integration from chromium @ https://crrev.com/336230

Adds linux direct rendering capability via mesa gbm.

Refactored gpu_platform_support (and _host) to allow different
implementations of messaging transport between host and gpu.

drm_cursor is stubbed out.

Removed ScopedAllowIO in drm_host_display_manager and added
header documentation indicating where IO is performed.

Removed unused files:
 ui/ozone/common/gpu/ozone_gpu_message_generator*
 ui/ozone/common/gpu/ozone_gpu_messages.h

BUG=
R=jamesr@chromium.org, spang@chromium.org

Committed: https://chromium.googlesource.com/external/mojo/+/d6387093328f25c31bf5e2a7375418323e418029

[cdotstout, 2015-08-18 19:32:46]

cstout@chromium.org changed reviewers:
+ jamesr@chromium.org, spang@chromium.org

[cdotstout, 2015-08-18 19:32:48]

This really just part 1. Forthcoming CL will add support for mojo to the mojo
native_viewport service.

[jamesr, 2015-08-18 20:11:33]

where'd the ozone code here come from? could you put a backref in the patch
description?

lgtm

https://codereview.chromium.org/1285183008/diff/1/mojo/BUILD.gn
File mojo/BUILD.gn (right):

https://codereview.chromium.org/1285183008/diff/1/mojo/BUILD.gn#newcode54
mojo/BUILD.gn:54: if (use_ozone) {
do we need use_ozone to be toggleable within the mojo repo? i'd like to keep the
cross-product of configurations down. will the ozone path work on our linux
boxes?

https://codereview.chromium.org/1285183008/diff/1/services/native_viewport/pl...
File services/native_viewport/platform_viewport_x11.cc (right):

https://codereview.chromium.org/1285183008/diff/1/services/native_viewport/pl...
services/native_viewport/platform_viewport_x11.cc:148: float device_pixel_ratio)
override {
ick, can we avoid having this? or do we need this to have this to work with the
ozone stuff? the way chromium code handles device_pixel_ratio is really bad and
i don't want to repeat it any more than necessary

[spang, 2015-08-18 20:25:31]

lgtm

https://codereview.chromium.org/1285183008/diff/1/mojo/BUILD.gn
File mojo/BUILD.gn (right):

https://codereview.chromium.org/1285183008/diff/1/mojo/BUILD.gn#newcode54
mojo/BUILD.gn:54: if (use_ozone) {
On 2015/08/18 20:11:33, jamesr wrote:
> do we need use_ozone to be toggleable within the mojo repo? i'd like to keep
the
> cross-product of configurations down. will the ozone path work on our linux
> boxes?

Not yet, but with some work we could have an x11 platform in ozone. We also want
it in order to deprecate the OS_CHROMEOS && !USE_OZONE build.

https://codereview.chromium.org/1285183008/diff/1/services/native_viewport/pl...
File services/native_viewport/platform_viewport_x11.cc (right):

https://codereview.chromium.org/1285183008/diff/1/services/native_viewport/pl...
services/native_viewport/platform_viewport_x11.cc:148: float device_pixel_ratio)
override {
On 2015/08/18 20:11:33, jamesr wrote:
> ick, can we avoid having this? or do we need this to have this to work with
the
> ozone stuff? the way chromium code handles device_pixel_ratio is really bad
and
> i don't want to repeat it any more than necessary

We don't need it - it always passes 1.f. On CrOS it ends up getting sorted out
later by ash.

[cdotstout, 2015-08-18 21:09:49]

On 2015/08/18 20:25:31, spang wrote:
> lgtm
> 
> https://codereview.chromium.org/1285183008/diff/1/mojo/BUILD.gn
> File mojo/BUILD.gn (right):
> 
> https://codereview.chromium.org/1285183008/diff/1/mojo/BUILD.gn#newcode54
> mojo/BUILD.gn:54: if (use_ozone) {
> On 2015/08/18 20:11:33, jamesr wrote:
> > do we need use_ozone to be toggleable within the mojo repo? i'd like to keep
> the
> > cross-product of configurations down. will the ozone path work on our linux
> > boxes?
> 
> Not yet, but with some work we could have an x11 platform in ozone. We also
want
> it in order to deprecate the OS_CHROMEOS && !USE_OZONE build.

Yes let's go this route.

>
https://codereview.chromium.org/1285183008/diff/1/services/native_viewport/pl...
> File services/native_viewport/platform_viewport_x11.cc (right):
> 
>
https://codereview.chromium.org/1285183008/diff/1/services/native_viewport/pl...
> services/native_viewport/platform_viewport_x11.cc:148: float
device_pixel_ratio)
> override {
> On 2015/08/18 20:11:33, jamesr wrote:
> > ick, can we avoid having this? or do we need this to have this to work with
> the
> > ozone stuff? the way chromium code handles device_pixel_ratio is really bad
> and
> > i don't want to repeat it any more than necessary
> 
> We don't need it - it always passes 1.f. On CrOS it ends up getting sorted out
> later by ash.

Removed.

[cdotstout, 2015-08-18 23:46:59]

Committed patchset #3 (id:40001) manually as
d6387093328f25c31bf5e2a7375418323e418029.