Positions the launcher in the bottom left corner. Adds ShellDelegate

ui/aura_shell/launcher/launcher_model_observer.h

 // Copyright (c) 2011 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 UI_AURA_SHELL_LAUNCHER_MODEL_OBSERVER_H_
 #define UI_AURA_SHELL_LAUNCHER_MODEL_OBSERVER_H_
 #pragma once
 
 #include "ui/aura_shell/aura_shell_export.h"
 
 namespace aura_shell {
 
 class AURA_SHELL_EXPORT LauncherModelObserver {
  public:
   // Invoked after an item has been added to the model.
   virtual void LauncherItemAdded(int index) = 0;
 
   // Invoked after an item has been removed. |index| is the index the item was
   // at.
   virtual void LauncherItemRemoved(int index) = 0;
 
-  // Invoked when the selection changes.
-  virtual void LauncherSelectionChanged() = 0;
+  // Invoked when the images of an item change.
+  virtual void LauncherItemImagesChanged(int index) = 0;
 
  protected:
   virtual ~LauncherModelObserver() {}
 };
 
 }  // namespace aura_shell
 
 #endif  // UI_AURA_SHELL_LAUNCHER_MODEL_OBSERVER_H_