Password manager metrics: Persist the choice of site groups for reporting

We report some useful metrics related to save password prompt on a per-site
basis for 10 popular sites. For privacy reasons, we do not do it directly,
but we group all sites so that in each group multiple sites are present, and
we report only the group, not the site. OTOH, each site is in more groups, so
if we see changing signals for some groups, we can guess that something broke
for a site in their intersection (hopefully one site). More details are in
http://goo.gl/vUuFd5.

The important thing is, however, that each particular user reports each
particular site in a fixed group out of all groups possible, as mentioned
also in http://crbug.com/268980#c12. This was not so in the original
implementation, there the group was changed on each browser run.

This CL stores the choice of group in preferences to make it persistent.
This preference gets not synced or sent out in any way. Note that as isherman@
observed, using client ID for generating the choice is not good for privacy,
because the client ID gets sent out together with the metrics.

BUG=262215, 268980

Review URL: https://codereview.chromium.org/24602002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226208 0039d316-1c4b-4281-b951-d872f2087c98
Fix a bug where a tab closed immediately after a navigate fails to close.

The bug occurs when the navigation requires a new RVH and the navigation
completes in the new renderer before the old renderer finishes closing
the page. In this case the browser process swaps out the old renderer
and the close is dropped on the floor.

This fixes the bug by terminating the new RVH when closing the tab.

BUG=294697

Review URL: https://codereview.chromium.org/24977003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226209 0039d316-1c4b-4281-b951-d872f2087c98
Expose apps Chrome URL hosts.

chrome://apps will be displayed in chrome://chrome-urls and be suggested in
omnibox autocomplete.

BUG=301504
R=pkasting@chromium.org

Review URL: https://codereview.chromium.org/25228002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226210 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 226209
SVN changes up to revision 226210