DO NOT SUBMIT: Allow selection change update before beginBatchEdit

Allow selection change update before beginBatchEdit

Currently, selection changes immediately before beginBatchEdit() may be
merged into batch edit selection update which happens at endBatchEdit().

The reason is that it takes round-trip time to get update from previous
operation and if we increment mNumNestedBatchEdits in beginBatchEdit()
before the update from renderer process arrives at browser process,
then the update from operation will be ignored because
mNumNestedBatchEdits > 0.

This can be prevented if we block and update selection at outermost
beginBatchEdit() call.

BUG=643473

[Changwan Ryu, 2016-09-06 08:38:03]

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

[commit-bot: I haz the power, 2016-09-06 08:38:16]

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

[Changwan Ryu, 2016-09-06 08:57:26]

changwan@chromium.org changed reviewers:
+ aelias@chromium.org

[commit-bot: I haz the power, 2016-09-06 09:47:30]

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

[commit-bot: I haz the power, 2016-09-06 09:47:32]

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

[Changwan Ryu, 2016-09-07 08:13:17]

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

[commit-bot: I haz the power, 2016-09-07 08:13:32]

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

[Changwan Ryu, 2016-09-07 08:14:10]

This CL's tests are also fixed.

[commit-bot: I haz the power, 2016-09-07 09:02:12]

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

[commit-bot: I haz the power, 2016-09-07 09:02:12]

Dry run: This issue passed the CQ dry run.

[Changwan Ryu, 2016-09-21 00:57:28]

There are additional benefits with an alternative solution
(https://codereview.chromium.org/2309983002/), so dropping this one.

[Changwan Ryu, 2016-09-21 00:57:40]

Description was changed from

==========
Allow selection change update before beginBatchEdit

Currently, selection changes immediately before beginBatchEdit() may be
merged into batch edit selection update which happens at endBatchEdit().

The reason is that it takes round-trip time to get update from previous
operation and if we increment mNumNestedBatchEdits in beginBatchEdit()
before the update from renderer process arrives at browser process,
then the update from operation will be ignored because
mNumNestedBatchEdits > 0.

This can be prevented if we block and update selection at outermost
beginBatchEdit() call.

BUG=643473
==========

to

==========
Allow selection change update before beginBatchEdit

Currently, selection changes immediately before beginBatchEdit() may be
merged into batch edit selection update which happens at endBatchEdit().

The reason is that it takes round-trip time to get update from previous
operation and if we increment mNumNestedBatchEdits in beginBatchEdit()
before the update from renderer process arrives at browser process,
then the update from operation will be ignored because
mNumNestedBatchEdits > 0.

This can be prevented if we block and update selection at outermost
beginBatchEdit() call.

BUG=643473
==========