chromeos: Refactor shelf to create ShelfView earlier in startup

ash/public/interfaces/shelf.mojom

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 module ash.mojom;
 
 import "mojo/common/string16.mojom";
 import "skia/public/interfaces/bitmap.mojom";
 import "ui/events/mojo/event.mojom";
 
@@ skipping 55 matching lines @@
   SetAutoHideBehavior(ShelfAutoHideBehavior auto_hide, int64 display_id);
 
   // Pin and unpin items on the shelf, or update shelf item images.
   PinItem(ShelfItem item, associated ShelfItemDelegate delegate);
   UnpinItem(string app_id);
   SetItemImage(string app_id, skia.mojom.Bitmap image);
 };
 
 // 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.

[James Cook, 2017/05/16 21:32:35]

I think this could dramatically simplify ash/chrome communication. It doesn't
fully work in mash (e.g. crbug.com/721961)

[msw, 2017/05/16 22:41:59]

Acknowledged. Maybe file a bug to track that idea and cite it here?

[James Cook, 2017/05/17 16:16:12]

Done.

+  OnShelfInitialized(int64 display_id);
   OnAlignmentChanged(ShelfAlignment alignment, int64 display_id);
   OnAutoHideBehaviorChanged(ShelfAutoHideBehavior auto_hide, int64 display_id);
 };
 
 // ShelfItemDelegate handles shelf item selection, menu command execution, etc.
 interface ShelfItemDelegate {
   // Called when the user selects a shelf item. The event, display, and source
   // info should be provided if known; some implementations use these arguments.
   // Defaults: (nullptr, kInvalidDisplayId, LAUNCH_FROM_UNKNOWN)
   // The callback reports the action taken and any app menu items to show.
@@ skipping 42 matching lines @@
 struct ShelfItem {
   ShelfItemType type;       // The type of the shelf item.
   skia.mojom.Bitmap image;  // An icon image Bitmap, shown on the shelf.
   ShelfItemStatus status;   // The running/closed/etc. status of the item.
   ShelfID shelf_id;         // The id for the shelf item and its windows.
   mojo.common.mojom.String16 title;  // The title to display for tooltips, etc.
   bool shows_tooltip;       // Whether the tooltip should be shown on hover.
   bool pinned_by_policy;    // Whether the item is pinned by policy preferences,
                             // the user cannot un-pin these items.
 };