Re-land: Fix loading accessibility tree for child frame that's already loaded.

Re-land: Fix loading accessibility tree for child frame that's already loaded.

(Original issue: http://crrev.com/2299673002 - fixed test failures on Mac
by disabling accessibility between subsequent runs.)

Code leftover from the pre-OOPIF days was causing us to exit early from
the RenderAccessibilityImpl constructor for some child frames that were
already loaded. Everything worked fine if accessibility was already enabled
when loading the frame, but if the frame was already loaded and then
accessibility was enabled, this could cause it to fail to create an
accessibility tree.

The code in RenderAccessibilityImpl is no longer needed because now we
have exactly one accessibility tree per frame.

This wasn't caught by tests because we didn't cover both scenarios, we
always enabled accessibility first.

Added two variants of existing tests that load the page first and then
enable accessibility.

BUG=640231
TBR=dtseng@chromium.org

Committed: https://crrev.com/e3d6283c33ce68650657647a842f21eaacb15cd8
Cr-Commit-Position: refs/heads/master@{#416274}

[dmazzoni, 2016-09-01 19:51:48]

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

[commit-bot: I haz the power, 2016-09-01 19:52:18]

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, 2016-09-01 21:45:37]

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

[commit-bot: I haz the power, 2016-09-01 21:45:38]

Dry run: This issue passed the CQ dry run.

[dmazzoni, 2016-09-02 15:43:07]

The CQ bit was checked by dmazzoni@chromium.org

[commit-bot: I haz the power, 2016-09-02 15:43:23]

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, 2016-09-02 15:47:16]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-09-02 15:50:42]

Description was changed from

==========
Re-land: Fix loading accessibility tree for child frame that's already loaded.

(Original issue: http://crrev.com/2299673002 - fixed test failures on Mac
by disabling accessibility between subsequent runs.)

Code leftover from the pre-OOPIF days was causing us to exit early from
the RenderAccessibilityImpl constructor for some child frames that were
already loaded. Everything worked fine if accessibility was already enabled
when loading the frame, but if the frame was already loaded and then
accessibility was enabled, this could cause it to fail to create an
accessibility tree.

The code in RenderAccessibilityImpl is no longer needed because now we
have exactly one accessibility tree per frame.

This wasn't caught by tests because we didn't cover both scenarios, we
always enabled accessibility first.

Added two variants of existing tests that load the page first and then
enable accessibility.

BUG=640231
TBR=dtseng@chromium.org
==========

to

==========
Re-land: Fix loading accessibility tree for child frame that's already loaded.

(Original issue: http://crrev.com/2299673002 - fixed test failures on Mac
by disabling accessibility between subsequent runs.)

Code leftover from the pre-OOPIF days was causing us to exit early from
the RenderAccessibilityImpl constructor for some child frames that were
already loaded. Everything worked fine if accessibility was already enabled
when loading the frame, but if the frame was already loaded and then
accessibility was enabled, this could cause it to fail to create an
accessibility tree.

The code in RenderAccessibilityImpl is no longer needed because now we
have exactly one accessibility tree per frame.

This wasn't caught by tests because we didn't cover both scenarios, we
always enabled accessibility first.

Added two variants of existing tests that load the page first and then
enable accessibility.

BUG=640231
TBR=dtseng@chromium.org

Committed: https://crrev.com/e3d6283c33ce68650657647a842f21eaacb15cd8
Cr-Commit-Position: refs/heads/master@{#416274}
==========

[commit-bot: I haz the power, 2016-09-02 15:50:43]

Patchset 1 (id:??) landed as
https://crrev.com/e3d6283c33ce68650657647a842f21eaacb15cd8
Cr-Commit-Position: refs/heads/master@{#416274}

[dmazzoni, 2016-09-02 22:08:09]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/2302353005/ by dmazzoni@chromium.org.

The reason for reverting is: Leads to a lot of try flakes / flakes in general:


.