Fix a crash on Mac due to TextInputManager being null

Fix a crash on Mac due to TextInputManager being null

The reference to TextInputManager instance (owned by WebContentsImpl) in RenderWidgetHostView is alive as long as
  1) WebContents is alive,
  2) RenderWidgetHostView is registered with TextInputManager.

On Mac, WebContents destruction might not lead to immediate destruction of the RenderWidgetHostViewMac. Therefore,
there can be a period of time where (after WebContentsImpl is deleted) |text_input_manager_| is null. Then it is only
safe to check |text_input_manager_| before dereferencing it.

BUG=709864
Review-Url: https://codereview.chromium.org/2813493003
Cr-Commit-Position: refs/heads/master@{#463338}
Committed: https://chromium.googlesource.com/chromium/src/+/f50104bb610bec50956cfe363d08c9682b930ab9

[EhsanK, 2017-04-10 15:29:05]

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

[commit-bot: I haz the power, 2017-04-10 15:29:30]

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

[EhsanK, 2017-04-10 15:30:38]

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

[EhsanK, 2017-04-10 15:30:39]

Hello Avi,

PTAL.

Thanks!

https://codereview.chromium.org/2813493003/diff/1/content/browser/renderer_ho...
File content/browser/renderer_host/render_widget_host_view_mac.mm (right):

https://codereview.chromium.org/2813493003/diff/1/content/browser/renderer_ho...
content/browser/renderer_host/render_widget_host_view_mac.mm:567: return
GetTextInputManager() ? text_input_manager_->GetCompositionRangeInfo()
This is similar to lines 557 and 561 above. I think this will stop the crash.

[commit-bot: I haz the power, 2017-04-10 16:05:04]

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

[commit-bot: I haz the power, 2017-04-10 16:05:05]

Dry run: This issue passed the CQ dry run.

[Avi (use Gerrit), 2017-04-10 18:22:09]

LGTM

[EhsanK, 2017-04-10 18:24:05]

Thanks for the quick review even when OOO :)! I will CQ soon. Hopefully stopping
the crash. Thanks!

[EhsanK, 2017-04-10 18:24:10]

The CQ bit was checked by ekaramad@chromium.org

[commit-bot: I haz the power, 2017-04-10 18:25:00]

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, 2017-04-10 18:32:34]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1491848650150800, "parent_rev":
"4e433f99b03ba6fd056ac1b8bbc1edd8db95d94a", "commit_rev":
"f50104bb610bec50956cfe363d08c9682b930ab9"}

[commit-bot: I haz the power, 2017-04-10 18:36:46]

Description was changed from

==========
Fix a crash on Mac due to TextInputManager being null

The reference to TextInputManager instance (owned by WebContentsImpl) in
RenderWidgetHostView is alive as long as
  1) WebContents is alive,
  2) RenderWidgetHostView is registered with TextInputManager.

On Mac, WebContents destruction might not lead to immediate destruction of the
RenderWidgetHostViewMac. Therefore,
there can be a period of time where (after WebContentsImpl is deleted)
|text_input_manager_| is null. Then it is only
safe to check |text_input_manager_| before dereferencing it.

BUG=709864
==========

to

==========
Fix a crash on Mac due to TextInputManager being null

The reference to TextInputManager instance (owned by WebContentsImpl) in
RenderWidgetHostView is alive as long as
  1) WebContents is alive,
  2) RenderWidgetHostView is registered with TextInputManager.

On Mac, WebContents destruction might not lead to immediate destruction of the
RenderWidgetHostViewMac. Therefore,
there can be a period of time where (after WebContentsImpl is deleted)
|text_input_manager_| is null. Then it is only
safe to check |text_input_manager_| before dereferencing it.

BUG=709864

Review-Url: https://codereview.chromium.org/2813493003
Cr-Commit-Position: refs/heads/master@{#463338}
Committed:
https://chromium.googlesource.com/chromium/src/+/f50104bb610bec50956cfe363d08...
==========

[commit-bot: I haz the power, 2017-04-10 18:36:47]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/f50104bb610bec50956cfe363d08...