Moves MruWindowTracker to WmShell

ash/common/wm_shell.h

Index: ash/common/wm_shell.h
diff --git a/ash/common/wm_shell.h b/ash/common/wm_shell.h
index d111540cf7da655c1051edc4375f327ee5cfff7b..6c3a4934b1a1e89b8c6607eb04bed1065e77f9ea 100644
--- a/ash/common/wm_shell.h
+++ b/ash/common/wm_shell.h
@@ -18,6 +18,7 @@ class Rect;
 
 namespace ash {
 
+class MruWindowTracker;
 class SessionStateDelegate;
 class WindowResizer;
 class WmActivationObserver;
@@ -35,13 +36,13 @@ enum class WmUserMetricsAction;
 // Similar to ash::Shell. Eventually the two will be merged.
 class ASH_EXPORT WmShell {
  public:
-  virtual ~WmShell() {}
-
   // This is necessary for a handful of places that is difficult to plumb
   // through context.
   static void Set(WmShell* instance);
   static WmShell* Get();
 
+  virtual MruWindowTracker* GetMruWindowTracker() = 0;
+
   // Creates a new window used as a container of other windows. No painting is
   // done to the created window.
   virtual WmWindow* NewContainerWindow() = 0;
@@ -59,12 +60,6 @@ class ASH_EXPORT WmShell {
   // appropriate container in the returned window.
   virtual WmWindow* GetRootWindowForNewWindows() = 0;
 
-  // Returns the list of most recently used windows.
-  virtual std::vector<WmWindow*> GetMruWindowList() = 0;
-
-  // Returns the list of most recently used windows excluding modals.
-  virtual std::vector<WmWindow*> GetMruWindowListIgnoreModals() = 0;
-
   // Returns true if the first window shown on first run should be
   // unconditionally maximized, overriding the heuristic that normally chooses
   // the window size.
@@ -106,6 +101,9 @@ class ASH_EXPORT WmShell {
   virtual void AddOverviewModeObserver(WmOverviewModeObserver* observer) = 0;
   virtual void RemoveOverviewModeObserver(WmOverviewModeObserver* observer) = 0;
 
+ protected:
+  virtual ~WmShell() {}
+
  private:
   static WmShell* instance_;
 };