Force reset of RenderViewImpl zoom level.

Force reset of RenderViewImpl zoom level.

When navigation away from a page fails, the displayed error page uses
the zoom level of the current page since the underlying RenderViewImpl
is re-used without resetting its zoom level before displaying the error
page.

This CL forces the RenderViewImpl's zoom level to be reset to 0 whenever
the url being navigated to is unkown to the RenderViewImpl.

BUG=422464
Committed: https://crrev.com/263e86f88ffc1c8587a5d3141fbc5d6f0ca8519b
Cr-Commit-Position: refs/heads/master@{#300352}

[wjmaclean, 2014-10-20 19:19:59]

wjmaclean@chromium.org changed reviewers:
+ nasko@chromium.org

[wjmaclean, 2014-10-20 19:20:00]

nasko@ - Can you take a look at this? I believe you wrote the surrounding code.

I would like to add a test, but it needs access to the RenderFrame/View and I
couldn't find a good place to put it ... do you have any thoughts on that?

[nasko, 2014-10-20 20:35:22]

LGTM

[wjmaclean, 2014-10-20 20:42:35]

The CQ bit was checked by wjmaclean@chromium.org

[commit-bot: I haz the power, 2014-10-20 20:44:31]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/663203002/1

[commit-bot: I haz the power, 2014-10-20 22:22:30]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-10-20 22:23:20]

Patchset 1 (id:??) landed as
https://crrev.com/263e86f88ffc1c8587a5d3141fbc5d6f0ca8519b
Cr-Commit-Position: refs/heads/master@{#300352}