[ios] Add session saving support to clean skeleton.

ios/chrome/browser/browser_state/browser_state_keyed_service_factories.mm

Index: ios/chrome/browser/browser_state/browser_state_keyed_service_factories.mm
diff --git a/ios/chrome/browser/browser_state/browser_state_keyed_service_factories.mm b/ios/chrome/browser/browser_state/browser_state_keyed_service_factories.mm
index a87f1b14b37099885681c03fd8d98b5bd454a387..5faf7b4d1a22b8f97f1e55a75efc9de31ef9b017 100644
--- a/ios/chrome/browser/browser_state/browser_state_keyed_service_factories.mm
+++ b/ios/chrome/browser/browser_state/browser_state_keyed_service_factories.mm
@@ -46,6 +46,7 @@
 #include "ios/chrome/browser/translate/translate_accept_languages_factory.h"
 #include "ios/chrome/browser/undo/bookmark_undo_service_factory.h"
 #include "ios/chrome/browser/web_data_service_factory.h"
+#include "ios/shared/chrome/browser/ui/browser_list/browser_list_session_service_factory.h"

[sdefresne, 2017/05/04 14:52:35]

I'm still unconvinced the BrowserList is part of UI and think it is part of
model.

[marq (ping after 24h), 2017/05/09 10:18:59]

To me, it's "model" code in that it doesn't directly implement UI, but it's the
model representation of UI state (which tabs are grouped together). So
conceptually it's the "ui model" (as opposed to "data model"). I'm open to
discussion on this, however.

[sdefresne, 2017/05/11 15:57:59]

It still seems strange that this is the only file from a /ui/ sub-directory
included in that file.

In addition, desktop make a difference between a Browser and a BrowserWindow
(Browser is model, BrowserWindow is UI and wraps a Browser, with lots of
intermediate classes like BrowserView and BrowserFrame).

[rohitrao (ping after 24h), 2017/05/15 11:56:03]

It owns Browser, which in turn owns a dispatcher and a broadcaster.  I think
both of those are solidly part of the UI, so we're in a weird state.  I do agree
that Browser and BrowserList are more model than ui, but I don't know how to
resolve this contradiction.

 
 #if !defined(__has_feature) || !__has_feature(objc_arc)
 #error "This file requires ARC support."
@@ -86,6 +87,7 @@ void EnsureBrowserStateKeyedServiceFactoriesBuilt() {
   ios::WebDataServiceFactory::GetInstance();
   ios::WebHistoryServiceFactory::GetInstance();
   AuthenticationServiceFactory::GetInstance();
+  BrowserListSessionServiceFactory::GetInstance();
   DesktopPromotionSyncServiceFactory::GetInstance();
   IOSChromeGCMProfileServiceFactory::GetInstance();
   IOSChromeLargeIconCacheFactory::GetInstance();