ash: Move AppList support to ShelfWidget, expose ShelfWidget in WmShelf

ash/first_run/first_run_helper_impl.cc

Index: ash/first_run/first_run_helper_impl.cc
diff --git a/ash/first_run/first_run_helper_impl.cc b/ash/first_run/first_run_helper_impl.cc
index 71b1e6cab9f1d3606b8574165597c593f9bf8eb7..0acba3a52963147ce8e7fec65a314422d8ee5c3f 100644
--- a/ash/first_run/first_run_helper_impl.cc
+++ b/ash/first_run/first_run_helper_impl.cc
@@ -5,9 +5,11 @@
 #include "ash/first_run/first_run_helper_impl.h"
 
 #include "ash/common/shelf/app_list_button.h"
-#include "ash/common/shelf/shelf.h"
+#include "ash/common/shelf/shelf_widget.h"
+#include "ash/common/shelf/wm_shelf.h"
 #include "ash/common/shell_window_ids.h"
 #include "ash/common/system/tray/system_tray.h"
+#include "ash/common/wm_lookup.h"
 #include "ash/shell.h"
 #include "base/logging.h"
 #include "ui/app_list/views/app_list_view.h"
@@ -53,8 +55,9 @@ views::Widget* FirstRunHelperImpl::GetOverlayWidget() {
 }
 
 gfx::Rect FirstRunHelperImpl::GetAppListButtonBounds() {
-  Shelf* shelf = Shelf::ForPrimaryDisplay();
-  AppListButton* app_button = shelf->GetAppListButton();
+  WmShelf* shelf =
+      WmShelf::ForWindow(WmLookup::Get()->GetWindowForWidget(widget_));

[msw, 2016/08/29 22:58:08]

nit/q: Why look up widget_ instead of using WmShell::GetPrimaryRootWindow()?

[James Cook, 2016/08/29 23:49:25]

No particularly good reason. Switched to WmShell::GetPrimaryRootWindow().

+  AppListButton* app_button = shelf->shelf_widget()->GetAppListButton();
   return app_button->GetBoundsInScreen();
 }