Refactors maximize mode event handling into its own class

ash/common/wm_shell.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_COMMON_WM_SHELL_H_
 #define ASH_COMMON_WM_SHELL_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 20 matching lines @@
 class ShellObserver;
 class SystemTrayDelegate;
 class WindowResizer;
 class WindowSelectorController;
 class WmActivationObserver;
 class WmDisplayObserver;
 class SystemTrayNotifier;
 class WmWindow;
 
 namespace wm {
+class MaximizeModeEventHandler;
 class WindowState;
 }
 
 // Similar to ash::Shell. Eventually the two will be merged.
 class ASH_EXPORT WmShell {
  public:
   // This is necessary for a handful of places that is difficult to plumb
   // through context.
   static void Set(WmShell* instance);
   static WmShell* Get();
@@ skipping 75 matching lines @@
 
   virtual void RecordUserMetricsAction(UserMetricsAction action) = 0;
 
   // Returns a WindowResizer to handle dragging. |next_window_resizer| is
   // the next WindowResizer in the WindowResizer chain. This may return
   // |next_window_resizer|.
   virtual std::unique_ptr<WindowResizer> CreateDragWindowResizer(
       std::unique_ptr<WindowResizer> next_window_resizer,
       wm::WindowState* window_state) = 0;
 
+  virtual std::unique_ptr<wm::MaximizeModeEventHandler>
+  CreateMaximizeModeEventHandler() = 0;
+
   // Called when the overview mode is about to be started (before the windows
   // get re-arranged).
   virtual void OnOverviewModeStarting() = 0;
 
   // Called after overview mode has ended.
   virtual void OnOverviewModeEnded() = 0;
 
   virtual AccessibilityDelegate* GetAccessibilityDelegate() = 0;
 
   virtual SessionStateDelegate* GetSessionStateDelegate() = 0;
@@ skipping 34 matching lines @@
   std::unique_ptr<SystemTrayNotifier> system_tray_notifier_;
   std::unique_ptr<SystemTrayDelegate> system_tray_delegate_;
   std::unique_ptr<WindowSelectorController> window_selector_controller_;
 
   bool simulate_modal_window_open_for_testing_ = false;
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_WM_SHELL_H_