Unobserve the host WebContents of an ExtensionHost on destruction, to prevent

Unobserve the host WebContents of an ExtensionHost on destruction, to prevent
re-entrant WebContentsObserver events running during ExtensionHost destruction.
This also reverts the fix I made in crbug.com/456920 since this should cover it.

BUG=459239, 456920
R=mek@chromium.org

Committed: https://crrev.com/89a8dc89370d682d3d5dc8d7dda94b19b750b7a2
Cr-Commit-Position: refs/heads/master@{#316671}

[Marijn Kruisselbrink, 2015-02-17 20:17:44]

lgtm

https://codereview.chromium.org/930413002/diff/20001/extensions/browser/exten...
File extensions/browser/extension_host.cc (right):

https://codereview.chromium.org/930413002/diff/20001/extensions/browser/exten...
extensions/browser/extension_host.cc:170:
content::WebContentsObserver::Observe(NULL);
nullptr? or was this intentional to stay consistent with the rest of the file?

[not at google - send to devlin, 2015-02-17 21:16:55]

New patchsets have been uploaded after l-g-t-m from mek@chromium.org

[not at google - send to devlin, 2015-02-17 21:17:34]

https://codereview.chromium.org/930413002/diff/20001/extensions/browser/exten...
File extensions/browser/extension_host.cc (right):

https://codereview.chromium.org/930413002/diff/20001/extensions/browser/exten...
extensions/browser/extension_host.cc:170:
content::WebContentsObserver::Observe(NULL);
On 2015/02/17 20:17:44, Marijn Kruisselbrink wrote:
> nullptr? or was this intentional to stay consistent with the rest of the file?

It's never intentional :-) (and I fixed the rest of the file too, only a couple
of other places).

[not at google - send to devlin, 2015-02-17 21:17:37]

The CQ bit was checked by kalman@chromium.org

[commit-bot: I haz the power, 2015-02-17 21:19:19]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/930413002/40001

[commit-bot: I haz the power, 2015-02-17 22:22:09]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2015-02-17 22:22:49]

Patchset 3 (id:??) landed as
https://crrev.com/89a8dc89370d682d3d5dc8d7dda94b19b750b7a2
Cr-Commit-Position: refs/heads/master@{#316671}