Pass a TaskRunner through ViewsDelegate to put AX init on FILE thread

Pass a TaskRunner through ViewsDelegate to put AX init on FILE thread

Adds an interface to ViewsDelegate to get a TaskRunner for a thread that
can be used for initialization tasks (implemented using the FILE thread),
and passes that TaskRunner to the ATK accessibility initialization code,
which currently does I/O on the main thread, causing a perf issue.

This change just adds the plumbing to get the TaskRunner there.
This will be followed up by this change that actually moves the initialization
to the other thread: https://codereview.chromium.org/1028553003/

BUG=468112
Committed: https://crrev.com/b9bfea7758f5fbda076d5873f5cf10a5f44598cf
Cr-Commit-Position: refs/heads/master@{#327117}

[dmazzoni, 2015-04-24 17:44:57]

dmazzoni@chromium.org changed reviewers:
+ sky@chromium.org

[sky, 2015-04-24 20:52:29]

https://codereview.chromium.org/1089003003/diff/1/chrome/browser/ui/views/chr...
File chrome/browser/ui/views/chrome_views_delegate.cc (right):

https://codereview.chromium.org/1089003003/diff/1/chrome/browser/ui/views/chr...
chrome/browser/ui/views/chrome_views_delegate.cc:394: return
content::BrowserThread::GetMessageLoopProxyForThread(
Why do we want to run this on the file thread?

https://codereview.chromium.org/1089003003/diff/1/chrome/browser/ui/views/chr...
File chrome/browser/ui/views/chrome_views_delegate.h (right):

https://codereview.chromium.org/1089003003/diff/1/chrome/browser/ui/views/chr...
chrome/browser/ui/views/chrome_views_delegate.h:52:
scoped_refptr<base::TaskRunner> GetInitializationTaskRunner() override;
GetInitializationTaskRunner is very generic. The task-runner that is returned
likely depends on exactly what the task-runner is going to be used for. I'm
inclined to name this more specifically right now. If we need more we name it
more generically and add an enum. I'm specifically thinking of something like: 
GetTaskRunnerForAccessibilityInitialization.

[dmazzoni, 2015-04-24 21:23:43]

https://codereview.chromium.org/1089003003/diff/1/chrome/browser/ui/views/chr...
File chrome/browser/ui/views/chrome_views_delegate.cc (right):

https://codereview.chromium.org/1089003003/diff/1/chrome/browser/ui/views/chr...
chrome/browser/ui/views/chrome_views_delegate.cc:394: return
content::BrowserThread::GetMessageLoopProxyForThread(
On 2015/04/24 20:52:28, sky wrote:
> Why do we want to run this on the file thread?

It's the call to g_module_open in
ui/accessibility/platform/atk_util_auralinux.cc that needs to be on the file
thread.

https://codereview.chromium.org/1089003003/diff/1/chrome/browser/ui/views/chr...
File chrome/browser/ui/views/chrome_views_delegate.h (right):

https://codereview.chromium.org/1089003003/diff/1/chrome/browser/ui/views/chr...
chrome/browser/ui/views/chrome_views_delegate.h:52:
scoped_refptr<base::TaskRunner> GetInitializationTaskRunner() override;
On 2015/04/24 20:52:28, sky wrote:
> GetInitializationTaskRunner is very generic. The task-runner that is returned
> likely depends on exactly what the task-runner is going to be used for. I'm
> inclined to name this more specifically right now. If we need more we name it
> more generically and add an enum. I'm specifically thinking of something like:

> GetTaskRunnerForAccessibilityInitialization.

OK, if we want to be really specific, we should specify this is only for Aura
Linux; there's nothing blocking we have to do on other platforms.

Renamed GetTaskRunnerForAuraLinuxAccessibilityInit and ifdefed it to only that
build.

[sky, 2015-04-27 15:10:15]

LGTM

https://codereview.chromium.org/1089003003/diff/40001/chrome/browser/ui/views...
File chrome/browser/ui/views/chrome_views_delegate.cc (right):

https://codereview.chromium.org/1089003003/diff/40001/chrome/browser/ui/views...
chrome/browser/ui/views/chrome_views_delegate.cc:395: return
content::BrowserThread::GetMessageLoopProxyForThread(
Add your comment here about why this needs to be on the file thread.

[dmazzoni, 2015-04-27 19:52:05]

https://codereview.chromium.org/1089003003/diff/40001/chrome/browser/ui/views...
File chrome/browser/ui/views/chrome_views_delegate.cc (right):

https://codereview.chromium.org/1089003003/diff/40001/chrome/browser/ui/views...
chrome/browser/ui/views/chrome_views_delegate.cc:395: return
content::BrowserThread::GetMessageLoopProxyForThread(
On 2015/04/27 15:10:14, sky wrote:
> Add your comment here about why this needs to be on the file thread.

Done.

[dmazzoni, 2015-04-27 19:52:08]

The CQ bit was checked by dmazzoni@chromium.org

[dmazzoni, 2015-04-27 19:52:08]

The patchset sent to the CQ was uploaded after l-g-t-m from sky@chromium.org
Link to the patchset: https://codereview.chromium.org/1089003003/#ps60001
(title: "Add comment about FILE thread")

[commit-bot: I haz the power, 2015-04-27 19:52:44]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1089003003/60001

[commit-bot: I haz the power, 2015-04-27 20:02:32]

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

[commit-bot: I haz the power, 2015-04-27 20:02:35]

Try jobs failed on following builders:
  linux_chromium_gn_chromeos_rel on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)

[dmazzoni, 2015-04-27 20:22:00]

The CQ bit was checked by dmazzoni@chromium.org

[commit-bot: I haz the power, 2015-04-27 20:22:58]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1089003003/60001

[commit-bot: I haz the power, 2015-04-27 21:12:53]

Committed patchset #4 (id:60001)

[commit-bot: I haz the power, 2015-04-27 21:13:51]

Patchset 4 (id:??) landed as
https://crrev.com/b9bfea7758f5fbda076d5873f5cf10a5f44598cf
Cr-Commit-Position: refs/heads/master@{#327117}