Fix ProcessManagerTest.* flakiness.

Fix ProcessManagerTest.* flakiness.

Remove ProcessManager as DevToolsAgentHost observer during the manager's
destruction.
In ProcessManagerTest-s, we create multiple ProcessManager-s
and add as DevToolsAgentHost observer. If two process managers were
created at the same address, then DevToolsAgentHost will think that we
are adding the same ProcessManager as observer twice.
Remove ProcessManager as DevToolsAgentHost observer during the manager's
destruction to avoid that. Also that is the right thing to do to avoid
potential UAF of ProcessManager from DevToolsAgentHost.

BUG=712429
Test=Running
./out/Release/extensions_unittests --gtest_filter=ProcessManagerTest.*
should pass without any retry.

Review-Url: https://codereview.chromium.org/2838223002
Cr-Commit-Position: refs/heads/master@{#467104}
Committed: https://chromium.googlesource.com/chromium/src/+/f70b2eb9fb89130c5d8c9bdc91fc98b7e07964ad

[lazyboy, 2017-04-25 17:05:29]

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

[commit-bot: I haz the power, 2017-04-25 17:05:59]

Dry run: CQ is trying da patch.

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

[lazyboy, 2017-04-25 17:08:38]

lazyboy@chromium.org changed reviewers:
+ rdevlin.cronin@chromium.org

[commit-bot: I haz the power, 2017-04-25 18:00:32]

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

[commit-bot: I haz the power, 2017-04-25 18:00:33]

Dry run: This issue passed the CQ dry run.

[Devlin, 2017-04-25 20:25:36]

lgtm; good find!

[lazyboy, 2017-04-25 20:36:25]

The CQ bit was checked by lazyboy@chromium.org

[commit-bot: I haz the power, 2017-04-25 20:37:13]

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, 2017-04-25 20:42:14]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1493152585365380, "parent_rev":
"4e1f66f1c92879d5ae8b2f75273fc8e73975cdea", "commit_rev":
"1939f12cde99d433868134dd444da78f17087762"}

[commit-bot: I haz the power, 2017-04-25 20:42:32]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1493152585365380, "parent_rev":
"9812ae210992792ccc39965b3a40897b1f4c1e75", "commit_rev":
"f70b2eb9fb89130c5d8c9bdc91fc98b7e07964ad"}

[commit-bot: I haz the power, 2017-04-25 20:43:12]

Description was changed from

==========
Fix ProcessManagerTest.* flakiness.

Remove ProcessManager as DevToolsAgentHost observer during the manager's
destruction.
In ProcessManagerTest-s, we create multiple ProcessManager-s
and add as DevToolsAgentHost observer. If two process managers were
created at the same address, then DevToolsAgentHost will think that we
are adding the same ProcessManager as observer twice.
Remove ProcessManager as DevToolsAgentHost observer during the manager's
destruction to avoid that. Also that is the right thing to do to avoid
potential UAF of ProcessManager from DevToolsAgentHost.

BUG=712429
Test=Running
./out/Release/extensions_unittests --gtest_filter=ProcessManagerTest.*
should pass without any retry.
==========

to

==========
Fix ProcessManagerTest.* flakiness.

Remove ProcessManager as DevToolsAgentHost observer during the manager's
destruction.
In ProcessManagerTest-s, we create multiple ProcessManager-s
and add as DevToolsAgentHost observer. If two process managers were
created at the same address, then DevToolsAgentHost will think that we
are adding the same ProcessManager as observer twice.
Remove ProcessManager as DevToolsAgentHost observer during the manager's
destruction to avoid that. Also that is the right thing to do to avoid
potential UAF of ProcessManager from DevToolsAgentHost.

BUG=712429
Test=Running
./out/Release/extensions_unittests --gtest_filter=ProcessManagerTest.*
should pass without any retry.

Review-Url: https://codereview.chromium.org/2838223002
Cr-Commit-Position: refs/heads/master@{#467104}
Committed:
https://chromium.googlesource.com/chromium/src/+/f70b2eb9fb89130c5d8c9bdc91fc...
==========

[commit-bot: I haz the power, 2017-04-25 20:43:13]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/f70b2eb9fb89130c5d8c9bdc91fc...