Remove an incorrect DCHECK

Remove an incorrect DCHECK.

The method RenderWidget::GetInputMethodController() can return nullptr in
the following cases:
1- RenderWidget is swapped out.
2- There is no focused frame in the local root which accepts IME.
  2.1 There are no focused local frames.
  2.2 The focused local frame does not belong to the same local root as RenderWidget.
  2.3 The focused local frame cannot accept IME since WebWidget is not focused (e.g., switched tabs).

Therefore, to handle set composition IPC we should not assume controller can
never be nullptr. A valid repro case:
1- Create an OOPIF in a page.
2- Add input in OOPIF.
3- Write javascript code which would randomly take focus away from OOPIF.
4- Activate some IME and start typing.

Eventually, DCHECK fires because the IPC to set composition arrived after
the widget lost the focused frame.

BUG=578168
Committed: https://crrev.com/685eb79f0ce22cc6fcdd74a76f0dfc240e1eff34
Cr-Commit-Position: refs/heads/master@{#437904}

[EhsanK, 2016-12-08 23:26:42]

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

[commit-bot: I haz the power, 2016-12-08 23:27:04]

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

[EhsanK, 2016-12-08 23:32:28]

Description was changed from

==========
Remove an incorrect DCHECK.

The method RenderWidget::GetInputMethodController() can return nullptr in
the following cases:
1- RenderWidget is swapped out.
2- There is no focused frame on page which accepts IME.
  2.1 There is no focused frame in the Widget.
  2.2 There is a focused frame but the Widget does not have focus, i.e.,
switched tabs.

Therefore, to handle set composition IPC we should not assume controller can
never be nullptr. It actually can, e.g:
1- Create two OOPIFs in process B on a page in process A.
2- Add <input> and write some javascript code which would occasionally focus
one <input> and its window.
3- Activate IME and start typing.
4- Eventually, DCHECK fires because the IPC to set composition arrived after
the widget lost the focused frame.

BUG=578168
==========

to

==========
Remove an incorrect DCHECK.

The method RenderWidget::GetInputMethodController() can return nullptr in
the following cases:
1- RenderWidget is swapped out.
2- There is no focused frame in the local root which accepts IME.
  2.1 There are no focused local frames.
  2.2 The focused local frame does not belong to the same local root as
RenderWidget.
  2.3 The focused local frame cannot accept IME since WebWidget is not focused
(e.g., switched tabs).

Therefore, to handle set composition IPC we should not assume controller can
never be nullptr. A valid repro case:
1- Create an OOPIF in a page.
2- Add input in OOPIF.
3- Write javascript code which would randomly take focus away from OOPIF.
4- Activate some IME and start typing.

Eventually, DCHECK fires because the IPC to set composition arrived after
the widget lost the focused frame. 

BUG=578168
==========

[EhsanK, 2016-12-08 23:32:28]

ekaramad@chromium.org changed reviewers:
+ creis@chromium.org

[commit-bot: I haz the power, 2016-12-08 23:39:04]

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

[commit-bot: I haz the power, 2016-12-08 23:39:04]

Dry run: Try jobs failed on following builders:
  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...)

[EhsanK, 2016-12-09 03:59:57]

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

[commit-bot: I haz the power, 2016-12-09 04:00:12]

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, 2016-12-09 04:47:40]

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

[commit-bot: I haz the power, 2016-12-09 04:47:41]

Dry run: This issue passed the CQ dry run.

[EhsanK, 2016-12-09 06:22:43]

PTAL.

[Charlie Reis, 2016-12-09 19:37:09]

LGTM

[EhsanK, 2016-12-10 18:40:27]

The CQ bit was checked by ekaramad@chromium.org

[commit-bot: I haz the power, 2016-12-10 18:40:33]

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, 2016-12-10 20:19:59]

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

[commit-bot: I haz the power, 2016-12-10 20:20:00]

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...)

[EhsanK, 2016-12-11 03:36:38]

The CQ bit was checked by ekaramad@chromium.org

[commit-bot: I haz the power, 2016-12-11 03:36:51]

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, 2016-12-11 05:29:02]

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

[commit-bot: I haz the power, 2016-12-11 05:29:03]

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...)

[EhsanK, 2016-12-12 00:04:50]

The CQ bit was checked by ekaramad@chromium.org

[commit-bot: I haz the power, 2016-12-12 00:05:05]

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, 2016-12-12 01:31:13]

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

[commit-bot: I haz the power, 2016-12-12 01:31:15]

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...)

[EhsanK, 2016-12-12 01:32:47]

The CQ bit was unchecked by ekaramad@chromium.org

[EhsanK, 2016-12-12 01:32:47]

The CQ bit was checked by ekaramad@chromium.org

[commit-bot: I haz the power, 2016-12-12 01:33:04]

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, 2016-12-12 03:10:03]

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

[commit-bot: I haz the power, 2016-12-12 03:10:04]

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...)

[EhsanK, 2016-12-12 17:49:52]

The CQ bit was checked by ekaramad@chromium.org

[commit-bot: I haz the power, 2016-12-12 17:50:23]

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, 2016-12-12 18:31:26]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1481564992473440, "parent_rev":
"cf382913656ae15c01c9342f81edffdb8f2aedae", "commit_rev":
"291710d6f6243fd1abdc64f2a62323c3a11e3f97"}

[commit-bot: I haz the power, 2016-12-12 18:31:57]

Description was changed from

==========
Remove an incorrect DCHECK.

The method RenderWidget::GetInputMethodController() can return nullptr in
the following cases:
1- RenderWidget is swapped out.
2- There is no focused frame in the local root which accepts IME.
  2.1 There are no focused local frames.
  2.2 The focused local frame does not belong to the same local root as
RenderWidget.
  2.3 The focused local frame cannot accept IME since WebWidget is not focused
(e.g., switched tabs).

Therefore, to handle set composition IPC we should not assume controller can
never be nullptr. A valid repro case:
1- Create an OOPIF in a page.
2- Add input in OOPIF.
3- Write javascript code which would randomly take focus away from OOPIF.
4- Activate some IME and start typing.

Eventually, DCHECK fires because the IPC to set composition arrived after
the widget lost the focused frame. 

BUG=578168
==========

to

==========
Remove an incorrect DCHECK.

The method RenderWidget::GetInputMethodController() can return nullptr in
the following cases:
1- RenderWidget is swapped out.
2- There is no focused frame in the local root which accepts IME.
  2.1 There are no focused local frames.
  2.2 The focused local frame does not belong to the same local root as
RenderWidget.
  2.3 The focused local frame cannot accept IME since WebWidget is not focused
(e.g., switched tabs).

Therefore, to handle set composition IPC we should not assume controller can
never be nullptr. A valid repro case:
1- Create an OOPIF in a page.
2- Add input in OOPIF.
3- Write javascript code which would randomly take focus away from OOPIF.
4- Activate some IME and start typing.

Eventually, DCHECK fires because the IPC to set composition arrived after
the widget lost the focused frame. 

BUG=578168

Review-Url: https://codereview.chromium.org/2558303003
==========

[commit-bot: I haz the power, 2016-12-12 18:31:58]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-12-12 18:35:20]

Description was changed from

==========
Remove an incorrect DCHECK.

The method RenderWidget::GetInputMethodController() can return nullptr in
the following cases:
1- RenderWidget is swapped out.
2- There is no focused frame in the local root which accepts IME.
  2.1 There are no focused local frames.
  2.2 The focused local frame does not belong to the same local root as
RenderWidget.
  2.3 The focused local frame cannot accept IME since WebWidget is not focused
(e.g., switched tabs).

Therefore, to handle set composition IPC we should not assume controller can
never be nullptr. A valid repro case:
1- Create an OOPIF in a page.
2- Add input in OOPIF.
3- Write javascript code which would randomly take focus away from OOPIF.
4- Activate some IME and start typing.

Eventually, DCHECK fires because the IPC to set composition arrived after
the widget lost the focused frame. 

BUG=578168

Review-Url: https://codereview.chromium.org/2558303003
==========

to

==========
Remove an incorrect DCHECK.

The method RenderWidget::GetInputMethodController() can return nullptr in
the following cases:
1- RenderWidget is swapped out.
2- There is no focused frame in the local root which accepts IME.
  2.1 There are no focused local frames.
  2.2 The focused local frame does not belong to the same local root as
RenderWidget.
  2.3 The focused local frame cannot accept IME since WebWidget is not focused
(e.g., switched tabs).

Therefore, to handle set composition IPC we should not assume controller can
never be nullptr. A valid repro case:
1- Create an OOPIF in a page.
2- Add input in OOPIF.
3- Write javascript code which would randomly take focus away from OOPIF.
4- Activate some IME and start typing.

Eventually, DCHECK fires because the IPC to set composition arrived after
the widget lost the focused frame.

BUG=578168

Committed: https://crrev.com/685eb79f0ce22cc6fcdd74a76f0dfc240e1eff34
Cr-Commit-Position: refs/heads/master@{#437904}
==========

[commit-bot: I haz the power, 2016-12-12 18:35:21]

Patchset 1 (id:??) landed as
https://crrev.com/685eb79f0ce22cc6fcdd74a76f0dfc240e1eff34
Cr-Commit-Position: refs/heads/master@{#437904}