ozone: Allow ozone evdev/kvm features to be enabled without running on ChromeOS.

ozone: Allow ozone evdev/kvm features to be enabled without running on ChromeOS.
    
Adds a new "IsRunningAsSystemCompositor" flag for ChromeOS
builds. This flag can be used to enable ChromeOS system compositor
features without having to be running on a real ChromeOS device.
    
This is useful for testing purposes as it allows evdev input system
and the GBM ozone platform to be used on a workstation.
    
BUG=677267
Review-Url: https://codereview.chromium.org/2585633004
Cr-Commit-Position: refs/heads/master@{#442507}
Committed: https://chromium.googlesource.com/chromium/src/+/241589803c85731c3bd032ad828b3001300c3643

[reveman, 2016-12-16 16:46:41]

Description was changed from

==========
ozone: Allow ozone evdev/drm features to be used with running on ChromeOS.

Determine if these features should be used based on ozone platform
instead of if running on ChromeOS.

BUG=
TEST=
==========

to

==========
ozone: Allow ozone evdev/drm features to be used with running on ChromeOS.

NOT FOR REVIEW

Determine if these features should be used based on ozone platform
instead of if running on ChromeOS.

BUG=
TEST=
==========

[reveman, 2016-12-19 22:06:19]

Description was changed from

==========
ozone: Allow ozone evdev/drm features to be used with running on ChromeOS.

NOT FOR REVIEW

Determine if these features should be used based on ozone platform
instead of if running on ChromeOS.

BUG=
TEST=
==========

to

==========
ozone: Allow ozone evdev/kvm features to be enabled without running on ChromeOS.
    
Adds a new "IsRunningAsSystemCompositor" flag to SysInfo for ChromeOS
builds. This flag can be used to enable ChromeOS system compositor
features without having to be running on a real ChromeOS device.
    
This is useful for testing purposes as it allows evdev input system
and the GBM ozone platform to be used on a workstation.
    
BUG=
TEST=
==========

[reveman, 2016-12-30 16:18:20]

Description was changed from

==========
ozone: Allow ozone evdev/kvm features to be enabled without running on ChromeOS.
    
Adds a new "IsRunningAsSystemCompositor" flag to SysInfo for ChromeOS
builds. This flag can be used to enable ChromeOS system compositor
features without having to be running on a real ChromeOS device.
    
This is useful for testing purposes as it allows evdev input system
and the GBM ozone platform to be used on a workstation.
    
BUG=
TEST=
==========

to

==========
ozone: Allow ozone evdev/kvm features to be enabled without running on ChromeOS.
    
Adds a new "IsRunningAsSystemCompositor" flag to SysInfo for ChromeOS
builds. This flag can be used to enable ChromeOS system compositor
features without having to be running on a real ChromeOS device.
    
This is useful for testing purposes as it allows evdev input system
and the GBM ozone platform to be used on a workstation.
    
BUG=677267
==========

[reveman, 2016-12-30 16:18:31]

reveman@chromium.org changed reviewers:
+ rjkroege@chromium.org

[rjkroege, 2017-01-02 01:26:27]

https://codereview.chromium.org/2585633004/diff/60001/ash/shell.cc
File ash/shell.cc (right):

https://codereview.chromium.org/2585633004/diff/60001/ash/shell.cc#newcode619
ash/shell.cc:619: if (!display_initialized &&
base::SysInfo::IsRunningAsSystemCompositor()) {
does this risk breaking support for ChromeOS Chrome on X11? 

I realize that we will get rid of that configuration eventually and be
ozone-everywhere but I didn't think that we were yet?

https://codereview.chromium.org/2585633004/diff/60001/base/sys_info.h
File base/sys_info.h (right):

https://codereview.chromium.org/2585633004/diff/60001/base/sys_info.h#newcode136
base/sys_info.h:136: static bool IsRunningAsSystemCompositor();
nitpicking that you can ignore: what you mean here is using ozone yes?

https://codereview.chromium.org/2585633004/diff/60001/chromeos/settings/timez...
File chromeos/settings/timezone_settings.cc (right):

https://codereview.chromium.org/2585633004/diff/60001/chromeos/settings/timez...
chromeos/settings/timezone_settings.cc:471: if
(base::SysInfo::IsRunningAsSystemCompositor()) {
Are you sure that you should have changed this one?

[reveman, 2017-01-02 07:11:32]

ptal

https://codereview.chromium.org/2585633004/diff/60001/ash/shell.cc
File ash/shell.cc (right):

https://codereview.chromium.org/2585633004/diff/60001/ash/shell.cc#newcode619
ash/shell.cc:619: if (!display_initialized &&
base::SysInfo::IsRunningAsSystemCompositor()) {
On 2017/01/02 at 01:26:27, rjkroege wrote:
> does this risk breaking support for ChromeOS Chrome on X11? 
> 
> I realize that we will get rid of that configuration eventually and be
ozone-everywhere but I didn't think that we were yet?

ChromeOS Chrome on X11 should still work just fine. Chrome is not running as a
system compositor in that case so you'd avoid passing the flag that makes this
return true in that case.

https://codereview.chromium.org/2585633004/diff/60001/base/sys_info.h
File base/sys_info.h (right):

https://codereview.chromium.org/2585633004/diff/60001/base/sys_info.h#newcode136
base/sys_info.h:136: static bool IsRunningAsSystemCompositor();
On 2017/01/02 at 01:26:27, rjkroege wrote:
> nitpicking that you can ignore: what you mean here is using ozone yes?

I'm expected that we'll keep having support for running ozone Chrome in a non
system compositor mode. E.g. the existing x11 and wayland platforms.

FYI, my initial version of this patch was explicitly checking "ozone_platform ==
gbm" but I decided that it was much easier and more useful to just separate this
into a flag. We can always improve the auto-detection logic for this in the
future.

https://codereview.chromium.org/2585633004/diff/60001/chromeos/settings/timez...
File chromeos/settings/timezone_settings.cc (right):

https://codereview.chromium.org/2585633004/diff/60001/chromeos/settings/timez...
chromeos/settings/timezone_settings.cc:471: if
(base::SysInfo::IsRunningAsSystemCompositor()) {
On 2017/01/02 at 01:26:27, rjkroege wrote:
> Are you sure that you should have changed this one?

hm, maybe the stub impl works better on non-chromeos linux machines. changed to
that in latest patch. "stub" is probably not the best name for that impl..

[rjkroege, 2017-01-03 18:53:00]

lgtm

[reveman, 2017-01-03 22:03:07]

reveman@chromium.org changed reviewers:
+ sky@chromium.org, thakis@chromium.org

[reveman, 2017-01-03 22:03:08]

+thakis for base/
+sky for ash/ chrome/ ui/ services/

[reveman, 2017-01-03 22:03:16]

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

[commit-bot: I haz the power, 2017-01-03 22:03:52]

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

[Nico, 2017-01-03 22:40:14]

why is this in base/? "compositor" doesn't seem very base-y.

[commit-bot: I haz the power, 2017-01-03 23:08:58]

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

[commit-bot: I haz the power, 2017-01-03 23:08:58]

Dry run: This issue passed the CQ dry run.

[reveman, 2017-01-03 23:38:08]

On 2017/01/03 at 22:40:14, thakis wrote:
> why is this in base/? "compositor" doesn't seem very base-y.

"system compositor" is just the best term I could come up with for describing
the mode where Chrome has direct access to hardware and running directly on the
kernel without any windowing system in between. Not really compositing related.
IsRunningOnOSWithoutWM is another option.

Anyhow, moving this out of base/ is not a bad idea. I considered putting it in
ui/ozone/ when writing this but as it required some DEPS changes I figured it
was best to start with this simple approach and discuss it as part of the code
review. Happy to move it to ui/ozone or similar if we agree that's the best
place for this.

[Nico, 2017-01-03 23:39:32]

ui/ sounds more appropriate from a distance, at least :-)

On Tue, Jan 3, 2017 at 6:38 PM, <reveman@chromium.org> wrote:

> On 2017/01/03 at 22:40:14, thakis wrote:
> > why is this in base/? "compositor" doesn't seem very base-y.
>
> "system compositor" is just the best term I could come up with for
> describing
> the mode where Chrome has direct access to hardware and running directly
> on the
> kernel without any windowing system in between. Not really compositing
> related.
> IsRunningOnOSWithoutWM is another option.
>
> Anyhow, moving this out of base/ is not a bad idea. I considered putting
> it in
> ui/ozone/ when writing this but as it required some DEPS changes I figured
> it
> was best to start with this simple approach and discuss it as part of the
> code
> review. Happy to move it to ui/ozone or similar if we agree that's the best
> place for this.
>
> https://codereview.chromium.org/2585633004/
>

-- 
You received this message because you are subscribed to the Google Groups
"Chromium-reviews" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to chromium-reviews+unsubscribe@chromium.org.

[sky, 2017-01-04 00:14:14]

On 2017/01/03 23:38:08, reveman wrote:
> On 2017/01/03 at 22:40:14, thakis wrote:
> > why is this in base/? "compositor" doesn't seem very base-y.
> 
> "system compositor" is just the best term I could come up with for describing
> the mode where Chrome has direct access to hardware and running directly on
the
> kernel without any windowing system in between. Not really compositing
related.
> IsRunningOnOSWithoutWM is another option.
> 
> Anyhow, moving this out of base/ is not a bad idea. I considered putting it in
> ui/ozone/ when writing this but as it required some DEPS changes I figured it
> was best to start with this simple approach and discuss it as part of the code
> review. Happy to move it to ui/ozone or similar if we agree that's the best
> place for this.

If it's only used from ozone code, ui/ozone SGTM

[sky, 2017-01-04 00:19:45]

Alternatively would it make sense to put this in chromeos/ or
ui/chromeos? All the files you've touched are chromeos specific.

  -Scott

On Tue, Jan 3, 2017 at 4:14 PM,  <sky@chromium.org> wrote:
> On 2017/01/03 23:38:08, reveman wrote:
>> On 2017/01/03 at 22:40:14, thakis wrote:
>> > why is this in base/? "compositor" doesn't seem very base-y.
>>
>> "system compositor" is just the best term I could come up with for
>> describing
>> the mode where Chrome has direct access to hardware and running directly
>> on
> the
>> kernel without any windowing system in between. Not really compositing
> related.
>> IsRunningOnOSWithoutWM is another option.
>>
>> Anyhow, moving this out of base/ is not a bad idea. I considered putting
>> it in
>> ui/ozone/ when writing this but as it required some DEPS changes I figured
>> it
>> was best to start with this simple approach and discuss it as part of the
>> code
>> review. Happy to move it to ui/ozone or similar if we agree that's the
>> best
>> place for this.
>
> If it's only used from ozone code, ui/ozone SGTM
>
> https://codereview.chromium.org/2585633004/

-- 
You received this message because you are subscribed to the Google Groups
"Chromium-reviews" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to chromium-reviews+unsubscribe@chromium.org.

[reveman, 2017-01-04 00:37:56]

On 2017/01/04 at 00:19:45, sky wrote:
> Alternatively would it make sense to put this in chromeos/ or
> ui/chromeos? All the files you've touched are chromeos specific.

If we want to use this for more than testing and development in the future then
ui/ozone makes more sense as allowing the system compositor mode that chromeos
target supports today to also be used on linux shouldn't really require a
chromeos target build. It should ideally be a linux build with ozone+gbm and
various ui features enabled that currently only gets built for chromeos.

I'll move it to ui/ozone/. If prefer chromeos/ or ui/chromeos/ then let me know.

[sky, 2017-01-04 00:38:50]

I'm fine with ui/ozone.

On Tue, Jan 3, 2017 at 4:37 PM,  <reveman@chromium.org> wrote:
> On 2017/01/04 at 00:19:45, sky wrote:
>> Alternatively would it make sense to put this in chromeos/ or
>> ui/chromeos? All the files you've touched are chromeos specific.
>
> If we want to use this for more than testing and development in the future
> then
> ui/ozone makes more sense as allowing the system compositor mode that
> chromeos
> target supports today to also be used on linux shouldn't really require a
> chromeos target build. It should ideally be a linux build with ozone+gbm and
> various ui features enabled that currently only gets built for chromeos.
>
> I'll move it to ui/ozone/. If prefer chromeos/ or ui/chromeos/ then let me
> know.
>
> https://codereview.chromium.org/2585633004/

-- 
You received this message because you are subscribed to the Google Groups
"Chromium-reviews" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to chromium-reviews+unsubscribe@chromium.org.

[reveman, 2017-01-04 12:30:25]

Description was changed from

==========
ozone: Allow ozone evdev/kvm features to be enabled without running on ChromeOS.
    
Adds a new "IsRunningAsSystemCompositor" flag to SysInfo for ChromeOS
builds. This flag can be used to enable ChromeOS system compositor
features without having to be running on a real ChromeOS device.
    
This is useful for testing purposes as it allows evdev input system
and the GBM ozone platform to be used on a workstation.
    
BUG=677267
==========

to

==========
ozone: Allow ozone evdev/kvm features to be enabled without running on ChromeOS.
    
Adds a new "IsRunningAsSystemCompositor" flag for ChromeOS
builds. This flag can be used to enable ChromeOS system compositor
features without having to be running on a real ChromeOS device.
    
This is useful for testing purposes as it allows evdev input system
and the GBM ozone platform to be used on a workstation.
    
BUG=677267
==========

[reveman, 2017-01-04 12:37:17]

I decided to move this to chromeos/ after all. Long term we might want to extend
the OzonePlatform API for this. However, that requires also changing the current
code that depends on this value to not depend on it before the ozone platform
has been initialized. I think starting with this and then adding the
OzonePlatform API and incrementally converting code over to that is the best
approach.

ptal.

[reveman, 2017-01-04 12:37:52]

reveman@chromium.org changed reviewers:
+ oshima@chromium.org

[reveman, 2017-01-04 12:37:53]

+oshima for chromeos/

[sky, 2017-01-04 16:39:06]

I'm surprised you don't need to update deps in any BUILD.gn files for the
ui/display changes.

[reveman, 2017-01-05 04:47:20]

On 2017/01/04 at 16:39:06, sky wrote:
> I'm surprised you don't need to update deps in any BUILD.gn files for the
ui/display changes.

Good catch. Added missing deps changes to services/ui/display/BUILD.gn and
ui/display/manager/BUILD.gn in latest patch. Ptal.

[reveman, 2017-01-05 04:47:26]

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

[commit-bot: I haz the power, 2017-01-05 04:47:40]

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, 2017-01-05 04:51:46]

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

[commit-bot: I haz the power, 2017-01-05 04:51:47]

Dry run: Try jobs failed on following builders:
  android_clang_dbg_recipe on master.tryserver.chromium.android (JOB_FAILED,
https://build.chromium.org/p/tryserver.chromium.android/builders/android_clan...)
  android_compile_dbg on master.tryserver.chromium.android (JOB_FAILED,
https://build.chromium.org/p/tryserver.chromium.android/builders/android_comp...)
  android_n5x_swarming_rel on master.tryserver.chromium.android (JOB_FAILED,
https://build.chromium.org/p/tryserver.chromium.android/builders/android_n5x_...)
  cast_shell_android on master.tryserver.chromium.android (JOB_FAILED,
https://build.chromium.org/p/tryserver.chromium.android/builders/cast_shell_a...)
  linux_android_rel_ng on master.tryserver.chromium.android (JOB_FAILED,
https://build.chromium.org/p/tryserver.chromium.android/builders/linux_androi...)
  linux_chromium_asan_rel_ng on master.tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)
  linux_chromium_rel_ng on master.tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)

[reveman, 2017-01-05 05:21:53]

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

[commit-bot: I haz the power, 2017-01-05 05:22:08]

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, 2017-01-05 06:44:03]

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

[commit-bot: I haz the power, 2017-01-05 06:44:04]

Dry run: Try jobs failed on following builders:
  android_n5x_swarming_rel on master.tryserver.chromium.android (JOB_FAILED,
https://build.chromium.org/p/tryserver.chromium.android/builders/android_n5x_...)

[sky, 2017-01-05 17:13:34]

LGTM

[oshima, 2017-01-05 22:43:57]

https://codereview.chromium.org/2585633004/diff/140001/chromeos/chromeos_swit...
File chromeos/chromeos_switches.cc (right):

https://codereview.chromium.org/2585633004/diff/140001/chromeos/chromeos_swit...
chromeos/chromeos_switches.cc:425: const char kDisableSystemCompositorMode[] =
"disable-system-compositor-mode";
optional suggestion: FeatureList instead of two flags?

https://codereview.chromium.org/2585633004/diff/140001/chromeos/system/device...
File chromeos/system/devicemode.cc (right):

https://codereview.chromium.org/2585633004/diff/140001/chromeos/system/device...
chromeos/system/devicemode.cc:37: LAZY_INSTANCE_INITIALIZER;
Do you need lazy instance?

Since this never change during runtime, a local static inside
IsRunningAsSystemComopsitor is sufficient?

[reveman, 2017-01-06 08:15:15]

ptal

https://codereview.chromium.org/2585633004/diff/140001/chromeos/chromeos_swit...
File chromeos/chromeos_switches.cc (right):

https://codereview.chromium.org/2585633004/diff/140001/chromeos/chromeos_swit...
chromeos/chromeos_switches.cc:425: const char kDisableSystemCompositorMode[] =
"disable-system-compositor-mode";
On 2017/01/05 at 22:43:57, oshima wrote:
> optional suggestion: FeatureList instead of two flags?

I changed to a single flag in latest patch as I don't think we need the ability
to disable this when running on chromeos.

https://codereview.chromium.org/2585633004/diff/140001/chromeos/system/device...
File chromeos/system/devicemode.cc (right):

https://codereview.chromium.org/2585633004/diff/140001/chromeos/system/device...
chromeos/system/devicemode.cc:37: LAZY_INSTANCE_INITIALIZER;
On 2017/01/05 at 22:43:57, oshima wrote:
> Do you need lazy instance?
> 
> Since this never change during runtime, a local static inside
IsRunningAsSystemComopsitor is sufficient?

Done. I assume it's OK to rely on the compiler's thread-safe initialization of
statics as you suggested this. Never clear to me if that was OK or not in
chromium code. We better not compile with --fno-threadsafe-statics..

[oshima, 2017-01-09 19:09:12]

lgtm

https://codereview.chromium.org/2585633004/diff/140001/chromeos/system/device...
File chromeos/system/devicemode.cc (right):

https://codereview.chromium.org/2585633004/diff/140001/chromeos/system/device...
chromeos/system/devicemode.cc:37: LAZY_INSTANCE_INITIALIZER;
On 2017/01/06 08:15:14, reveman wrote:
> On 2017/01/05 at 22:43:57, oshima wrote:
> > Do you need lazy instance?
> > 
> > Since this never change during runtime, a local static inside
> IsRunningAsSystemComopsitor is sufficient?
> 
> Done. I assume it's OK to rely on the compiler's thread-safe initialization of
> statics as you suggested this. Never clear to me if that was OK or not in
> chromium code. We better not compile with --fno-threadsafe-statics.. 

CommandLine isn't thread safe, so the original code is already thread unsafe,
although it shouldn't be a real issue because it won't be modified once
initialized, and it'll be always initialized to the same value.

[reveman, 2017-01-09 22:51:49]

The CQ bit was checked by reveman@chromium.org

[reveman, 2017-01-09 22:51:50]

Thanks for the reviews

https://codereview.chromium.org/2585633004/diff/140001/chromeos/system/device...
File chromeos/system/devicemode.cc (right):

https://codereview.chromium.org/2585633004/diff/140001/chromeos/system/device...
chromeos/system/devicemode.cc:37: LAZY_INSTANCE_INITIALIZER;
On 2017/01/09 at 19:09:12, oshima wrote:
> On 2017/01/06 08:15:14, reveman wrote:
> > On 2017/01/05 at 22:43:57, oshima wrote:
> > > Do you need lazy instance?
> > > 
> > > Since this never change during runtime, a local static inside
> > IsRunningAsSystemComopsitor is sufficient?
> > 
> > Done. I assume it's OK to rely on the compiler's thread-safe initialization
of
> > statics as you suggested this. Never clear to me if that was OK or not in
> > chromium code. We better not compile with --fno-threadsafe-statics.. 
> 
> CommandLine isn't thread safe, so the original code is already thread unsafe,
although it shouldn't be a real issue because it won't be modified once
initialized, and it'll be always initialized to the same value.

CommandLine::HasSwitch is const so should be thread-safe unless Chromium is
actually modifying the command line after startup, no? Either way, this is
currently only used from the main thread so shouldn't be an issue in practice.

[reveman, 2017-01-09 22:51:50]

The patchset sent to the CQ was uploaded after l-g-t-m from
rjkroege@chromium.org, sky@chromium.org
Link to the patchset: https://codereview.chromium.org/2585633004/#ps160001
(title: "avoid use of lazy instance and remove disable flag")

[commit-bot: I haz the power, 2017-01-09 22:52:48]

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, 2017-01-09 22:55:43]

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

[commit-bot: I haz the power, 2017-01-09 22:55:46]

Try jobs failed on following builders:
  ios-device on master.tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/ios-device/builds...)
  ios-device-xcode-clang on master.tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/ios-device-xcode-...)
  ios-simulator on master.tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/ios-simulator/bui...)
  ios-simulator-xcode-clang on master.tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/ios-simulator-xco...)
  mac_chromium_rel_ng on master.tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_rel_...)

[reveman, 2017-01-10 03:25:21]

The CQ bit was checked by reveman@chromium.org

[reveman, 2017-01-10 03:25:21]

The patchset sent to the CQ was uploaded after l-g-t-m from
rjkroege@chromium.org, oshima@chromium.org, sky@chromium.org
Link to the patchset: https://codereview.chromium.org/2585633004/#ps180001
(title: "rebase")

[commit-bot: I haz the power, 2017-01-10 03:25:48]

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, 2017-01-10 05:58:51]

CQ is committing da patch.

Bot data: {"patchset_id": 180001, "attempt_start_ts": 1484018721154250,
"parent_rev": "544796c61fc9f18a8cb1e8fe0b01e5d4d9585895", "commit_rev":
"241589803c85731c3bd032ad828b3001300c3643"}

[commit-bot: I haz the power, 2017-01-10 05:59:18]

Description was changed from

==========
ozone: Allow ozone evdev/kvm features to be enabled without running on ChromeOS.
    
Adds a new "IsRunningAsSystemCompositor" flag for ChromeOS
builds. This flag can be used to enable ChromeOS system compositor
features without having to be running on a real ChromeOS device.
    
This is useful for testing purposes as it allows evdev input system
and the GBM ozone platform to be used on a workstation.
    
BUG=677267
==========

to

==========
ozone: Allow ozone evdev/kvm features to be enabled without running on ChromeOS.
    
Adds a new "IsRunningAsSystemCompositor" flag for ChromeOS
builds. This flag can be used to enable ChromeOS system compositor
features without having to be running on a real ChromeOS device.
    
This is useful for testing purposes as it allows evdev input system
and the GBM ozone platform to be used on a workstation.
    
BUG=677267

Review-Url: https://codereview.chromium.org/2585633004
Cr-Commit-Position: refs/heads/master@{#442507}
Committed:
https://chromium.googlesource.com/chromium/src/+/241589803c85731c3bd032ad828b...
==========

[commit-bot: I haz the power, 2017-01-10 05:59:19]

Committed patchset #10 (id:180001) as
https://chromium.googlesource.com/chromium/src/+/241589803c85731c3bd032ad828b...