[ios] Unregister CRWWebController delegates in -close.

[ios] Unregister CRWWebController delegates in -close.

With ARC, the order in which -dealloc is invoker is sometimes changed.
This means that some of CRWWebController delegates may end up calling
methods of CRWWebController between call to -close and -dealloc (until
the autorelease pool is cleared).

Since WebStateImpl calls CRWWebController -close just before releasing
its reference, and CRWWebController becomes unusable once -close has
been called (as -navigationManagerImpl will return nullptr), this does
not introduce an API change of CRWWebController while ensuring that
the delegate registration happens as part of WebStateImpl destruction.

Fixes the crash that caused the revert of http://crrev.com/2846233002/
with the following callstack (truncated):

  0   org.chromium.gtest.generic-unit-test  0x000000010169d83a -[CRWWebController setNavigationItemTitle:] + 266
  1   org.chromium.gtest.generic-unit-test  0x000000010169b2df -[CRWWebController nativeContent:titleDidChange:] + 47
  2   org.chromium.gtest.generic-unit-test  0x0000000101e545c3 -[StaticHtmlViewController observeValueForKeyPath:ofObject:change:context:] + 515
  3   com.apple.Foundation            0x000000010e3ee70c NSKeyValueNotifyObserver + 351
  4   com.apple.Foundation            0x000000010e3edfa7 NSKeyValueDidChange + 495
  5   com.apple.Foundation            0x000000010e3be00e -[NSObject(NSKeyValueObserverNotification) didChangeValueForKey:] + 118
  6   com.apple.WebKit                0x000000010fcb356a WebKit::PageLoadState::commitChanges() + 1538
  ...

BUG=None

Review-Url: https://codereview.chromium.org/2854943003
Cr-Commit-Position: refs/heads/master@{#469313}
Committed: https://chromium.googlesource.com/chromium/src/+/0197d1982c7b408050b03cd37882ea2209d45986

[sdefresne, 2017-05-03 12:25:13]

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

[commit-bot: I haz the power, 2017-05-03 12:25:25]

Dry run: CQ is trying da patch.

Follow status at:
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[sdefresne, 2017-05-03 12:25:38]

sdefresne@chromium.org changed reviewers:
+ michaeldo@chromium.org, stkhapugin@chromium.org

[sdefresne, 2017-05-03 12:25:38]

michaeldo: please take a look.
stkhapugin: FYI

[commit-bot: I haz the power, 2017-05-03 12:39:46]

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

[commit-bot: I haz the power, 2017-05-03 12:39:47]

Dry run: This issue passed the CQ dry run.

[michaeldo, 2017-05-03 16:13:01]

Thank you for the explanation in the CL. lgtm.

[sdefresne, 2017-05-04 12:01:48]

The CQ bit was checked by sdefresne@chromium.org

[commit-bot: I haz the power, 2017-05-04 12:01:54]

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, 2017-05-04 12:05:43]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1493899308075560, "parent_rev":
"6bac5f64f82e95a97fb1cba2fbc9bd8ed8bc8983", "commit_rev":
"0197d1982c7b408050b03cd37882ea2209d45986"}

[commit-bot: I haz the power, 2017-05-04 12:05:57]

Description was changed from

==========
[ios] Unregister CRWWebController delegates in -close.

With ARC, the order in which -dealloc is invoker is sometimes changed.
This means that some of CRWWebController delegates may end up calling
methods of CRWWebController between call to -close and -dealloc (until
the autorelease pool is cleared).

Since WebStateImpl calls CRWWebController -close just before releasing
its reference, and CRWWebController becomes unusable once -close has
been called (as -navigationManagerImpl will return nullptr), this does
not introduce an API change of CRWWebController while ensuring that
the delegate registration happens as part of WebStateImpl destruction.

Fixes the crash that caused the revert of http://crrev.com/2846233002/
with the following callstack (truncated):

  0   org.chromium.gtest.generic-unit-test  0x000000010169d83a
-[CRWWebController setNavigationItemTitle:] + 266
  1   org.chromium.gtest.generic-unit-test  0x000000010169b2df
-[CRWWebController nativeContent:titleDidChange:] + 47
  2   org.chromium.gtest.generic-unit-test  0x0000000101e545c3
-[StaticHtmlViewController observeValueForKeyPath:ofObject:change:context:] +
515
  3   com.apple.Foundation            0x000000010e3ee70c
NSKeyValueNotifyObserver + 351
  4   com.apple.Foundation            0x000000010e3edfa7 NSKeyValueDidChange +
495
  5   com.apple.Foundation            0x000000010e3be00e
-[NSObject(NSKeyValueObserverNotification) didChangeValueForKey:] + 118
  6   com.apple.WebKit                0x000000010fcb356a
WebKit::PageLoadState::commitChanges() + 1538
  ...

BUG=None
==========

to

==========
[ios] Unregister CRWWebController delegates in -close.

With ARC, the order in which -dealloc is invoker is sometimes changed.
This means that some of CRWWebController delegates may end up calling
methods of CRWWebController between call to -close and -dealloc (until
the autorelease pool is cleared).

Since WebStateImpl calls CRWWebController -close just before releasing
its reference, and CRWWebController becomes unusable once -close has
been called (as -navigationManagerImpl will return nullptr), this does
not introduce an API change of CRWWebController while ensuring that
the delegate registration happens as part of WebStateImpl destruction.

Fixes the crash that caused the revert of http://crrev.com/2846233002/
with the following callstack (truncated):

  0   org.chromium.gtest.generic-unit-test  0x000000010169d83a
-[CRWWebController setNavigationItemTitle:] + 266
  1   org.chromium.gtest.generic-unit-test  0x000000010169b2df
-[CRWWebController nativeContent:titleDidChange:] + 47
  2   org.chromium.gtest.generic-unit-test  0x0000000101e545c3
-[StaticHtmlViewController observeValueForKeyPath:ofObject:change:context:] +
515
  3   com.apple.Foundation            0x000000010e3ee70c
NSKeyValueNotifyObserver + 351
  4   com.apple.Foundation            0x000000010e3edfa7 NSKeyValueDidChange +
495
  5   com.apple.Foundation            0x000000010e3be00e
-[NSObject(NSKeyValueObserverNotification) didChangeValueForKey:] + 118
  6   com.apple.WebKit                0x000000010fcb356a
WebKit::PageLoadState::commitChanges() + 1538
  ...

BUG=None

Review-Url: https://codereview.chromium.org/2854943003
Cr-Commit-Position: refs/heads/master@{#469313}
Committed:
https://chromium.googlesource.com/chromium/src/+/0197d1982c7b408050b03cd37882...
==========

[commit-bot: I haz the power, 2017-05-04 12:05:57]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/0197d1982c7b408050b03cd37882...