Make launching apps from shelf more intuitive

ash/shelf/wm_shelf.h

 // 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.
 
 #ifndef ASH_SHELF_WM_SHELF_H_
 #define ASH_SHELF_WM_SHELF_H_
 
 #include <memory>
 
 #include "ash/ash_export.h"
@@ skipping 105 matching lines @@
 
   // Returns the screen bounds of the item for the specified window. If there is
   // no item for the specified window an empty rect is returned.
   gfx::Rect GetScreenBoundsOfItemIconForWindow(WmWindow* window);
 
   // Launch a 0-indexed shelf item in the shelf. A negative index launches the
   // last shelf item in the shelf.
   static void LaunchShelfItem(int item_index);
 
   // Activates the shelf item specified by the index in the list of shelf items.
   static void ActivateShelfItem(int item_index);

[stevenjb, 2017/05/22 17:55:28]

Is this still called? Maybe note where/why we do not always call 
ActivateShelfItemInDisplay? (Or if there are not a lot of examples, maybe just
remove this and pass display::kInvalidDisplayId in those instances).

[weidongg, 2017/05/23 16:37:46]

There are 40 occurrences of this function, so should I do the refactor like
removing ActivateShelfItemInDisplay and adding display_id parameter to
ActivateShelfItem?

 
+  // Activates the shelf item specified by the index in the list of shelf items
+  // in the display identified by |display_id|.

[Mr4D (OOO till 08-26), 2017/05/22 15:02:28]

on the display ...?

[weidongg, 2017/05/23 16:37:46]

Done.

+  static void ActivateShelfItemInDisplay(int item_index, int64_t display_id);
+
   // Handles a gesture |event| coming from a source outside the shelf widget
   // (e.g. the status area widget). Allows support for behaviors like toggling
   // auto-hide with a swipe, even if that gesture event hits another window.
   // Returns true if the event was handled.
   bool ProcessGestureEvent(const ui::GestureEvent& event);
 
   void AddObserver(WmShelfObserver* observer);
   void RemoveObserver(WmShelfObserver* observer);
 
   void NotifyShelfIconPositionsChanged();
@@ skipping 41 matching lines @@
   // Forwards touch gestures on a bezel sensor to the shelf.
   // TODO(mash): Facilitate simliar functionality in mash: crbug.com/636647
   std::unique_ptr<ShelfBezelEventHandler> bezel_event_handler_;
 
   DISALLOW_COPY_AND_ASSIGN(WmShelf);
 };
 
 }  // namespace ash
 
 #endif  // ASH_SHELF_WM_SHELF_H_