[rAC, OSX] Switch NSTextField to NSTextView

This is the first step of switching the entire suggestion text to a
single NSTextView. This is needed to enable several formatting changes
that were the result of UX review.

R=rsesek@chromium.org
BUG=277125

Review URL: https://codereview.chromium.org/58853010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@234630 0039d316-1c4b-4281-b951-d872f2087c98
Abort prerenders which try to create two navigation entries.

We do not currently patch up the history correctly. Let's try to fix this by
just aborting prerenders which do this, rather than complicating the history
merge function. UMA will tell us if this is a problem and if this case turns
out to be important.

This does not affect the following:
- Calls to location.replace.
- <meta http-equiv=refresh> redirects with a timeout under 1 second.
- Code which sets location.href before the load event.

BUG=305660
TEST=PrerenderBrowserTest.PrerenderNewNavigationEntry
     PrerenderBrowserTest.PrerenderLocationReplaceNavigateToFirst
     PrerenderBrowserTest.PrerenderLocationReplaceNavigateToSecond

Review URL: https://codereview.chromium.org/68213005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@234631 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 234631