App list: Added DCHECK for custom page when switching profiles.

App list: Added DCHECK for custom page when switching profiles.

This checks that the custom page's web contents belongs to the current
profile. This DCHECK would previously have failed when switching
profiles, but it should now always be true since crbug.com/392763 has
been resolved.

BUG=392763
Committed: https://crrev.com/535001b191a973f9615a2692831e7fdc357a6c08
Cr-Commit-Position: refs/heads/master@{#303806}

[Matt Giuca, 2014-11-12 07:06:51]

mgiuca@chromium.org changed reviewers:
+ tapted@chromium.org

[Matt Giuca, 2014-11-12 07:06:51]

This DCHECK seems to be working fine now (as of r291852).

[tapted, 2014-11-12 07:16:00]

lgtm. I guess these will never be incognito (so no need for
profile_->IsSameProfile(..))

[Matt Giuca, 2014-11-12 08:07:17]

The CQ bit was checked by mgiuca@chromium.org

[commit-bot: I haz the power, 2014-11-12 08:07:41]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/720683003/1

[commit-bot: I haz the power, 2014-11-12 09:01:34]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-11-12 09:02:21]

Patchset 1 (id:??) landed as
https://crrev.com/535001b191a973f9615a2692831e7fdc357a6c08
Cr-Commit-Position: refs/heads/master@{#303806}