Remove WebContentsImplTest::CrossSiteNavigationCanceled

Removed WebContentsImplTest::CrossSiteNavigationCanceled

This test checks that if a new navigation does not commit after the
current renderer has run its unload handler this does not leave the WebContents
in a stuck state. However, following
https://codereview.chromium.org/464593003/, the current renderer will only run
its unload handler after teh new navigation has committed. Therefore, this test
is no longer applicable.

BUG=402020
Committed: https://crrev.com/8dce417852ca909fedb7a36e35c1173b9c157dab
Cr-Commit-Position: refs/heads/master@{#322552}

[clamy, 2015-03-26 15:35:20]

clamy@chromium.org changed reviewers:
+ creis@chromium.org

[clamy, 2015-03-26 15:35:20]

@creis: PTAL

[Charlie Reis, 2015-03-26 16:53:57]

Yep, looks stale, so thanks for the cleanup.  LGTM.

[clamy, 2015-03-27 10:23:23]

The CQ bit was checked by clamy@chromium.org

[commit-bot: I haz the power, 2015-03-27 10:23:44]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1035963003/1

[commit-bot: I haz the power, 2015-03-27 11:10:32]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-03-27 11:11:55]

Patchset 1 (id:??) landed as
https://crrev.com/8dce417852ca909fedb7a36e35c1173b9c157dab
Cr-Commit-Position: refs/heads/master@{#322552}