chromeos: Refactor shelf to create ShelfView earlier in startup

ash/public/interfaces/shelf.mojom

Index: ash/public/interfaces/shelf.mojom
diff --git a/ash/public/interfaces/shelf.mojom b/ash/public/interfaces/shelf.mojom
index 10127072e8934aa5737e124cc0ed9ba2eb746219..aaf9966f0e68f1a88f46f9164a8e1b4524219272 100644
--- a/ash/public/interfaces/shelf.mojom
+++ b/ash/public/interfaces/shelf.mojom
@@ -73,7 +73,9 @@ interface ShelfController {
 
 // ShelfObserver is notified on shelf changes; used to persist profile settings.
 interface ShelfObserver {
-  OnShelfCreated(int64 display_id);
+  // TODO(jamescook): Eliminate all these methods and use the ash pref service
+  // to observe and to set prefs. http://crbug.com/723085
+  OnShelfInitialized(int64 display_id);
   OnAlignmentChanged(ShelfAlignment alignment, int64 display_id);
   OnAutoHideBehaviorChanged(ShelfAutoHideBehavior auto_hide, int64 display_id);
 };