Re-land: Reimplement automation API on top of C++-backed AXTree.

Re-land: Reimplement automation API on top of C++-backed AXTree.

Original review: https://codereview.chromium.org/1155183006
Landed in: r335183
Reverted in: r335343 (bug 502311)

BUG=495323, 502311
Committed: https://crrev.com/1777fbdbd234ddc8e19d4ba3a42cfd3234b8a158
Cr-Commit-Position: refs/heads/master@{#339929}

[dmazzoni, 2015-07-13 21:27:59]

dmazzoni@chromium.org changed reviewers:
+ aboxhall@chromium.org, dcheng@chromium.org, dtseng@chromium.org,
kalman@chromium.org

[dcheng, 2015-07-13 21:58:45]

What are the changes from the original patch? Any chance you could upload the
original one so reviewers can diff between them?

[dmazzoni, 2015-07-14 20:52:25]

OK, ready. Patch Set 1 is the original patch, rebased. No changes at all.

Patch Set 2 fixes bug 502311, which was introduced when this change landed. The
bug was that in ui/accessibility/ax_tree.cc I moved the NodeWillBeDeleted
callback from after the deletion to before the deletion. However, this left a
window of time where root_ pointed to an invalid node and that led to a crash.
Patch Set 2 fixes this bug by updating root_ before deleting the old root, and
it adds a test for that case.

Everything else is still unchanged from the original patch.

[not at google - send to devlin, 2015-07-14 20:58:59]

nothing has changed for extensions, lgtm.

[dcheng, 2015-07-15 00:58:10]

lgtm

https://codereview.chromium.org/1231603009/diff/20001/content/browser/accessi...
File content/browser/accessibility/browser_accessibility_manager_unittest.cc
(right):

https://codereview.chromium.org/1231603009/diff/20001/content/browser/accessi...
content/browser/accessibility/browser_accessibility_manager_unittest.cc:1007:
NULL,
Nit: nullptr

[aboxhall, 2015-07-15 17:15:55]

lgtm

[dmazzoni, 2015-07-15 19:18:26]

The CQ bit was checked by dmazzoni@chromium.org

[dmazzoni, 2015-07-15 19:18:26]

The patchset sent to the CQ was uploaded after l-g-t-m from dcheng@chromium.org,
aboxhall@chromium.org, kalman@chromium.org
Link to the patchset: https://codereview.chromium.org/1231603009/#ps40001
(title: "NULL -> nullptr")

[commit-bot: I haz the power, 2015-07-15 19:22:18]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1231603009/40001

[commit-bot: I haz the power, 2015-07-15 20:28:57]

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

[commit-bot: I haz the power, 2015-07-15 20:28:58]

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

[dmazzoni, 2015-07-22 18:44:27]

Ready to land again now, all tests pass.

One more tiny fix in the latest patch set for David to review.

https://codereview.chromium.org/1231603009/diff/20001/content/browser/accessi...
File content/browser/accessibility/browser_accessibility_manager_unittest.cc
(right):

https://codereview.chromium.org/1231603009/diff/20001/content/browser/accessi...
content/browser/accessibility/browser_accessibility_manager_unittest.cc:1007:
NULL,
On 2015/07/15 00:58:10, dcheng wrote:
> Nit: nullptr

Done throughout this file.

[David Tseng, 2015-07-22 19:02:00]

lgtm



[dmazzoni, 2015-07-22 19:05:06]

The CQ bit was checked by dmazzoni@chromium.org

[dmazzoni, 2015-07-22 19:05:07]

The patchset sent to the CQ was uploaded after l-g-t-m from dcheng@chromium.org,
aboxhall@chromium.org, kalman@chromium.org
Link to the patchset: https://codereview.chromium.org/1231603009/#ps100001
(title: "Fix nested event sending in AutomationManagerAura")

[commit-bot: I haz the power, 2015-07-22 19:06:07]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1231603009/100001

[commit-bot: I haz the power, 2015-07-22 19:17:16]

Committed patchset #6 (id:100001)

[commit-bot: I haz the power, 2015-07-22 19:18:46]

Patchset 6 (id:??) landed as
https://crrev.com/1777fbdbd234ddc8e19d4ba3a42cfd3234b8a158
Cr-Commit-Position: refs/heads/master@{#339929}

[Alexei Svitkine (slow), 2015-07-23 14:36:16]

A revert of this CL (patchset #6 id:100001) has been created in
https://codereview.chromium.org/1251723003/ by asvitkine@chromium.org.

The reason for reverting is: Top crasher in today's canary - 74% of browser
crashes. Reverting per stability sheriff guidelines (go/stability-sheriff)..