Revert 195553 "Allow showing pending URL for new tab navigations..."

Revert 195553 "Allow showing pending URL for new tab navigations..."
Caused spike in renderer crashes.

> Allow showing pending URL for new tab navigations, but only if safe. 
> 
> We revert to showing the opener's URL if it modifies the content of the 
> initial blank page before the pending URL commits, to prevent URL spoofs. 
> 
> Implications: 
> - All renderer-initiated navigations now have pending NavigationEntries. 
> - GetURL and GetTitle use the visible entry, not active entry. 
> - The renderer notifies the browser if DOM mutations occur before first load. 
> 
> [Second attempt, after http://crrev.com/191277 was reverted.]
> 
> BUG=9682
> TEST=Open a slow link in a new tab. Destination URL should be visible and reloadable.
> 
> Review URL: https://chromiumcodereview.appspot.com/13846007

TBR=creis@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=195970

[Charlie Reis, 2013-04-24 01:27:18]

Committed patchset #1 manually as r195970.