Revert of Revert of [site isolation] cross-site transfers should track the RenderFrameHost

Revert of Revert of [site isolation] cross-site transfers should track the RenderFrameHost, not the View (patchset #1 of https://codereview.chromium.org/462083003/)

Reason for revert:
The CL turns out to be innocent. Reverting the revert

Original issue's description:
> Revert of [site isolation] cross-site transfers should track the RenderFrameHost, not the View (https://codereview.chromium.org/457003002/)
> 
> Reason for revert:
> Speculatively reverting CL in case it is causing WebNavigationApiTest.OpenTab to fail http://test-results.appspot.com/dashboards/flakiness_dashboard.html#group=%40ToT%20Chromium&testType=browser_tests&tests=WebNavigationApiTest.OpenTab
> 
> Original issue's description:
> > site isolation: cross-site transfers should track the RenderFrameHost, not the View
> > 
> > This fixes some issues that came up while debugging bug 400850, which inadvertently caused OOPIF-like view reuse in RenderFrameHostManagerTest.AllowTargetedNavigationsAfterSwap.
> > 
> > 1. Make navigation_suspended state be per-RenderFrameHost. What was happening, was that we'd suspend navigations on the non-main frame of the view, and upon resume, we'd switch frames.
> > 
> > 2. Make the map of pending cross site requests be a map of RenderFrameHost IDs instead of RenderViewHost IDs, instead of just assuming that it's the main frame of the view that's navigating.
> > 
> > 3. Add a pending_main_rfh() to the test apparatus, for use by unittests that query the navigation_suspended state.
> > 
> > BUG=304341, 400850
> > 
> > Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=288867
> 
> TBR=creis@chromium.org,nick@chromium.org
> NOTREECHECKS=true
> NOTRY=true
> BUG=304341, 400850
> 
> Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=289049

TBR=creis@chromium.org,nick@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=304341, 400850
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=289082

[pkotwicz, 2014-08-12 22:01:49]

Created Revert of Revert of [site isolation] cross-site transfers should track
the RenderFrameHost, not the View

[ncarter (slow), 2014-08-12 22:08:23]

LGTM, thanks

[commit-bot: I haz the power, 2014-08-12 22:10:52]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/pkotwicz@chromium.org/466933003/1

[commit-bot: I haz the power, 2014-08-12 22:19:39]

Change committed as 289082