sync: Add --enable-sync-sessions-v2 and necessary plumbing to use SessionsSyncManager.

chrome/browser/sync/profile_sync_components_factory_impl.cc

Index: chrome/browser/sync/profile_sync_components_factory_impl.cc
diff --git a/chrome/browser/sync/profile_sync_components_factory_impl.cc b/chrome/browser/sync/profile_sync_components_factory_impl.cc
index de90dd71e3c6f5a0d8b1b633bdcee1eeb5a24469..87a75e4f50e4a25b0f803bd7d6a91f5df816b26d 100644
--- a/chrome/browser/sync/profile_sync_components_factory_impl.cc
+++ b/chrome/browser/sync/profile_sync_components_factory_impl.cc
@@ -51,6 +51,7 @@
 #include "chrome/browser/sync/profile_sync_components_factory_impl.h"
 #include "chrome/browser/sync/profile_sync_service.h"
 #include "chrome/browser/sync/profile_sync_service_factory.h"
+#include "chrome/browser/sync/sessions2/session_data_type_controller2.h"
 #include "chrome/browser/themes/theme_service.h"
 #include "chrome/browser/themes/theme_service_factory.h"
 #include "chrome/browser/themes/theme_syncable_service.h"
@@ -100,6 +101,7 @@ using browser_sync::ProxyDataTypeController;
 using browser_sync::SearchEngineDataTypeController;
 using browser_sync::SessionChangeProcessor;
 using browser_sync::SessionDataTypeController;
+using browser_sync::SessionDataTypeController2;
 using browser_sync::SessionModelAssociator;
 using browser_sync::SharedChangeProcessor;
 using browser_sync::SyncBackendHost;
@@ -172,10 +174,15 @@ void ProfileSyncComponentsFactoryImpl::RegisterCommonDataTypes(
 
   // Session sync is enabled by default.  Register unless explicitly disabled.
   if (!command_line_->HasSwitch(switches::kDisableSyncTabs)) {
-    pss->RegisterDataTypeController(
-        new ProxyDataTypeController(syncer::PROXY_TABS));
-    pss->RegisterDataTypeController(
-        new SessionDataTypeController(this, profile_, pss));
+      pss->RegisterDataTypeController(
+          new ProxyDataTypeController(syncer::PROXY_TABS));
+    if (!command_line_->HasSwitch(switches::kEnableSyncSessionsV2)) {
+      pss->RegisterDataTypeController(
+          new SessionDataTypeController(this, profile_, pss));
+    } else {
+      pss->RegisterDataTypeController(
+          new SessionDataTypeController2(this, profile_, pss));
+    }
   }
 
   // Favicon sync is enabled by default. Register unless explicitly disabled.
@@ -397,12 +404,11 @@ base::WeakPtr<syncer::SyncableService> ProfileSyncComponentsFactoryImpl::
 #endif
     case syncer::FAVICON_IMAGES:
     case syncer::FAVICON_TRACKING: {
-      browser_sync::SessionModelAssociator* model_associator =
+      browser_sync::FaviconCache* favicons =
           ProfileSyncServiceFactory::GetForProfile(profile_)->
-              GetSessionModelAssociator();
-      if (!model_associator)
-        return base::WeakPtr<syncer::SyncableService>();
-      return model_associator->GetFaviconCache()->AsWeakPtr();
+              GetFaviconCache();
+      return favicons ? favicons->AsWeakPtr()
+                      : base::WeakPtr<syncer::SyncableService>();
     }
 #if defined(ENABLE_MANAGED_USERS)
     case syncer::MANAGED_USER_SETTINGS:
@@ -415,12 +421,15 @@ base::WeakPtr<syncer::SyncableService> ProfileSyncComponentsFactoryImpl::
     case syncer::ARTICLES:
       // TODO(nyquist) Hook up real syncer::SyncableService API here.
       return base::WeakPtr<syncer::SyncableService>();
+    case syncer::SESSIONS:
+      DCHECK(command_line_->HasSwitch(switches::kEnableSyncSessionsV2));
+      return ProfileSyncServiceFactory::GetForProfile(profile_)->
+          GetSessionsSyncableService()->AsWeakPtr();
     default:
       // The following datatypes still need to be transitioned to the
       // syncer::SyncableService API:
       // Bookmarks
       // Passwords
-      // Sessions
       // Typed URLs
       NOTREACHED();
       return base::WeakPtr<syncer::SyncableService>();