Lands http://codereview.chromium.org/9316065/ for Marja. I reviewed
this, so I'm using TBR to land it.

Don't crash if multiple SessionRestoreImpl:s refer to the same
Profile.

It shouldn't ever happen but it seems to happen anyway.

BUG=111238
TEST=NONE
TBR=sky@chromium.org
R=marja@chromium.org

Review URL: https://chromiumcodereview.appspot.com/9343005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@120648 0039d316-1c4b-4281-b951-d872f2087c98
void TabLoader::RegisterForNotifications(NavigationController* controller) {
  registrar_.Add(this, content::NOTIFICATION_WEB_CONTENTS_DESTROYED,
                 content::Source<WebContents>(controller->GetWebContents()));
  registrar_.Add(this, content::NOTIFICATION_LOAD_STOP,
                 content::Source<NavigationController>(controller));
  registrar_.Add(this, content::NOTIFICATION_LOAD_START,
                 content::Source<NavigationController>(controller));
  ++tab_count_;
}

void TabLoader::RegisterForNotifications(NavigationController* controller) {
  registrar_.Add(this, content::NOTIFICATION_WEB_CONTENTS_DESTROYED,
                 content::Source<WebContents>(controller->GetWebContents()));
  registrar_.Add(this, content::NOTIFICATION_LOAD_STOP,
                 content::Source<NavigationController>(controller));
  registrar_.Add(this, content::NOTIFICATION_LOAD_START,
                 content::Source<NavigationController>(controller));
  ++tab_count_;
}
