FBTF: Reaplly the TabRestoreService::Observer into its own file commit.

This means browser.h no longer includes a large chunk of the tab restore
system. Now with fixes to chromeos.

BUG=none
TEST=compiles
First Review URL: http://codereview.chromium.org/3296003

Review URL: http://codereview.chromium.org/3358005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@58382 0039d316-1c4b-4281-b951-d872f2087c98
23 files changed