mash: Remove ChromeLauncherController's |id_to_item_controller_map_|.

chrome/browser/ui/ash/launcher/arc_app_window_launcher_controller.cc

Index: chrome/browser/ui/ash/launcher/arc_app_window_launcher_controller.cc
diff --git a/chrome/browser/ui/ash/launcher/arc_app_window_launcher_controller.cc b/chrome/browser/ui/ash/launcher/arc_app_window_launcher_controller.cc
index d6e8f2e2499f857ff29190b78260f7cee1f8a596..ccee5f499d530f6d37de6267e72ccfb848f7203c 100644
--- a/chrome/browser/ui/ash/launcher/arc_app_window_launcher_controller.cc
+++ b/chrome/browser/ui/ash/launcher/arc_app_window_launcher_controller.cc
@@ -6,6 +6,7 @@
 #include <string>
 
 #include "ash/common/shelf/shelf_delegate.h"
+#include "ash/common/shelf/shelf_model.h"
 #include "ash/common/wm/maximize_mode/maximize_mode_controller.h"
 #include "ash/common/wm/window_state.h"
 #include "ash/common/wm_window.h"
@@ -659,7 +660,8 @@ ArcAppWindowLauncherController::AttachControllerToTask(
   if (!shelf_id) {
     owner()->CreateAppLauncherItem(std::move(controller), ash::STATUS_RUNNING);
   } else {
-    owner()->SetShelfItemDelegate(shelf_id, std::move(controller));
+    ash::ShelfModel* shelf_model = ash::Shell::Get()->shelf_model();
+    shelf_model->SetShelfItemDelegate(shelf_id, std::move(controller));

[James Cook, 2017/04/07 20:42:22]

optional: I would be OK with keeping a CLC::SetShelfItemDelegate() that forwards
through to shelf_model->SSID(). OTOH, if you think owner()->SetItemStatus() will
move out of CLC, then this is definitely the right way to go.

[msw, 2017/04/07 22:02:16]

Both belong on our ShelfController ash mojo interface in the long run, but we
might just use ShelfModel for a model mirroring approach. I'll keep these using
ShelfModel for now; unfortunately there will likely be some churn either way.
lmk if you'd prefer that I restore the CLC helpers; it is a bit of a toss up.

     owner()->SetItemStatus(shelf_id, ash::STATUS_RUNNING);
   }
   item_controller->AddTaskId(task_id);