Protect against |main_window_| being null.

Protect against |main_window_| being null.

BlinkTestController::OnAllServiceWorkersCleared method needs to be
protected against a scenario where |main_window_| is null (e.g. this
field can be reset inside DiscardMainWindow if web contents are
destroyed during the test;  this wasn't an issue before r480692, because
back then we would just send an IPC to a routing id of a destroyed
RenderViewHost).

BUG=735423
Review-Url: https://codereview.chromium.org/2946103003
Cr-Commit-Position: refs/heads/master@{#481570}
Committed: https://chromium.googlesource.com/chromium/src/+/8b3bc33806c5940f54f91f4c57736e8b90a85b03

[Łukasz Anforowicz, 2017-06-21 19:39:35]

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

[commit-bot: I haz the power, 2017-06-21 19:40:06]

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, 2017-06-21 23:07:15]

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

[commit-bot: I haz the power, 2017-06-21 23:07:15]

Dry run: This issue passed the CQ dry run.

[Łukasz Anforowicz, 2017-06-22 16:42:25]

Description was changed from

==========
Protect against |main_window_| being null.

BlinkTestController::OnAllServiceWorkersCleared method needs to be
protected against a scenario where |main_window_| is null (e.g. this
field can be reset inside DiscardMainWindow if web contents are
destroyed during the test).

BUG=735423
==========

to

==========
Protect against |main_window_| being null.

BlinkTestController::OnAllServiceWorkersCleared method needs to be
protected against a scenario where |main_window_| is null (e.g. this
field can be reset inside DiscardMainWindow if web contents are
destroyed during the test;  this wasn't an issue before r480692, because
back then we would just send an IPC to a routing id of a destroyed
RenderViewHost).

BUG=735423
==========

[Łukasz Anforowicz, 2017-06-22 16:46:44]

lukasza@chromium.org changed reviewers:
+ alexmos@chromium.org

[Łukasz Anforowicz, 2017-06-22 16:46:45]

Alex, could you PTAL?  This fixes a test-only crash/regression that was 1)
introduced by blink_test_controller.cc changes from r480692 [1] and 2) caught by
ClusterFuzz.  I've tested using ClusterFuzz's reproduction tool and the crash it
found no longer repros after this fix.

[1]
https://codereview.chromium.org/2940863005/diff/60001/content/shell/browser/l...

[alexmos, 2017-06-22 16:58:04]

LGTM

[Łukasz Anforowicz, 2017-06-22 16:58:40]

The CQ bit was checked by lukasza@chromium.org

[commit-bot: I haz the power, 2017-06-22 16:59:18]

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, 2017-06-22 17:03:49]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1498150720604140, "parent_rev":
"d2290e01a65d77cc3b21bbfe67295938f97f5e3e", "commit_rev":
"8b3bc33806c5940f54f91f4c57736e8b90a85b03"}

[commit-bot: I haz the power, 2017-06-22 17:04:03]

Description was changed from

==========
Protect against |main_window_| being null.

BlinkTestController::OnAllServiceWorkersCleared method needs to be
protected against a scenario where |main_window_| is null (e.g. this
field can be reset inside DiscardMainWindow if web contents are
destroyed during the test;  this wasn't an issue before r480692, because
back then we would just send an IPC to a routing id of a destroyed
RenderViewHost).

BUG=735423
==========

to

==========
Protect against |main_window_| being null.

BlinkTestController::OnAllServiceWorkersCleared method needs to be
protected against a scenario where |main_window_| is null (e.g. this
field can be reset inside DiscardMainWindow if web contents are
destroyed during the test;  this wasn't an issue before r480692, because
back then we would just send an IPC to a routing id of a destroyed
RenderViewHost).

BUG=735423

Review-Url: https://codereview.chromium.org/2946103003
Cr-Commit-Position: refs/heads/master@{#481570}
Committed:
https://chromium.googlesource.com/chromium/src/+/8b3bc33806c5940f54f91f4c5773...
==========

[commit-bot: I haz the power, 2017-06-22 17:04:06]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/8b3bc33806c5940f54f91f4c5773...