Converts MruWindowTracker to work with common types

ash/common/wm_window.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_WINDOW_H_
 #define ASH_COMMON_WM_WINDOW_H_
 
 #include <memory>
 #include <vector>
 
@@ skipping 36 matching lines @@
 // This class exists as a porting layer to allow ash/wm to work with
 // aura::Window or mus::Window. See aura::Window for details on the functions.
 class ASH_EXPORT WmWindow {
  public:
   // See comments in SetBoundsInScreen().
   enum class BoundsInScreenBehavior {
     USE_LOCAL_COORDINATES,
     USE_SCREEN_COORDINATES,
   };
 
+  using Windows = std::vector<WmWindow*>;
+
   WmWindow* GetRootWindow() {
     return const_cast<WmWindow*>(
         const_cast<const WmWindow*>(this)->GetRootWindow());
   }
   virtual const WmWindow* GetRootWindow() const = 0;
   virtual WmRootWindowController* GetRootWindowController() = 0;
 
   // TODO(sky): fix constness.
   virtual WmShell* GetShell() const = 0;
 
@@ skipping 58 matching lines @@
                                      const gfx::Rect& screen_bounds) = 0;
   virtual void AddChild(WmWindow* window) = 0;
 
   virtual WmWindow* GetParent() = 0;
 
   WmWindow* GetTransientParent() {
     return const_cast<WmWindow*>(
         const_cast<const WmWindow*>(this)->GetTransientParent());
   }
   virtual const WmWindow* GetTransientParent() const = 0;
-  virtual std::vector<WmWindow*> GetTransientChildren() = 0;
+  virtual Windows GetTransientChildren() = 0;
 
   virtual void SetLayoutManager(
       std::unique_ptr<WmLayoutManager> layout_manager) = 0;
   virtual WmLayoutManager* GetLayoutManager() = 0;
 
   // |type| is WindowVisibilityAnimationType. Has to be an int to match aura.
   virtual void SetVisibilityAnimationType(int type) = 0;
   virtual void SetVisibilityAnimationDuration(base::TimeDelta delta) = 0;
   virtual void SetVisibilityAnimationTransition(
       ::wm::WindowVisibilityAnimationTransition transition) = 0;
@@ skipping 74 matching lines @@
   virtual bool CanMaximize() const = 0;
   virtual bool CanMinimize() const = 0;
   virtual bool CanResize() const = 0;
   virtual bool CanActivate() const = 0;
 
   virtual void StackChildAtTop(WmWindow* child) = 0;
   virtual void StackChildAtBottom(WmWindow* child) = 0;
   virtual void StackChildAbove(WmWindow* child, WmWindow* target) = 0;
   virtual void StackChildBelow(WmWindow* child, WmWindow* target) = 0;
 
-  virtual std::vector<WmWindow*> GetChildren() = 0;
+  virtual Windows GetChildren() = 0;
 
   // Shows/hides the resize shadow. |component| is the component to show the
   // shadow for (one of the constants in ui/base/hit_test.h).
   virtual void ShowResizeShadow(int component) = 0;
   virtual void HideResizeShadow() = 0;
 
   // See description in SetBoundsInScreen().
   virtual void SetBoundsInScreenBehaviorForChildren(BoundsInScreenBehavior) = 0;
 
   // See description of SnapToPixelBoundaryIfNecessary().
@@ skipping 14 matching lines @@
   virtual void AddObserver(WmWindowObserver* observer) = 0;
   virtual void RemoveObserver(WmWindowObserver* observer) = 0;
 
  protected:
   virtual ~WmWindow() {}
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_WM_WINDOW_H_