mash: Support ShelfModel access in Chrome.

chrome/browser/ui/views/ash/chrome_browser_main_extra_parts_ash.cc

Index: chrome/browser/ui/views/ash/chrome_browser_main_extra_parts_ash.cc
diff --git a/chrome/browser/ui/views/ash/chrome_browser_main_extra_parts_ash.cc b/chrome/browser/ui/views/ash/chrome_browser_main_extra_parts_ash.cc
index 05888bc412f57370b467ba1d409b82ed746e8779..aab4bb8588fd54a98d1a620d393182338bc268c9 100644
--- a/chrome/browser/ui/views/ash/chrome_browser_main_extra_parts_ash.cc
+++ b/chrome/browser/ui/views/ash/chrome_browser_main_extra_parts_ash.cc
@@ -102,7 +102,6 @@ void ChromeBrowserMainExtraPartsAsh::PostProfileInit() {
   if (ash_util::IsRunningInMash()) {
     DCHECK(!ash::Shell::HasInstance());
     DCHECK(!ChromeLauncherController::instance());
-    // TODO(crbug.com/557406): Synchronize this ShelfModel with the one in Ash.
     chrome_shelf_model_ = base::MakeUnique<ash::ShelfModel>();
     chrome_launcher_controller_ = base::MakeUnique<ChromeLauncherController>(
         nullptr, chrome_shelf_model_.get());