Converts RootWindowLayoutManager to common types

ash/root_window_controller.h

Index: ash/root_window_controller.h
diff --git a/ash/root_window_controller.h b/ash/root_window_controller.h
index aee25aa675f09ccb0b116156103dc565b0dc5ae7..2cb22d133a85850d78065614447b150baaa32d67 100644
--- a/ash/root_window_controller.h
+++ b/ash/root_window_controller.h
@@ -57,7 +57,6 @@ class DesktopBackgroundWidgetController;
 class DockedWindowLayoutManager;
 class PanelLayoutManager;
 class RootWindowControllerCommon;
-class RootWindowLayoutManager;
 class Shelf;
 class ShelfLayoutManager;
 class ShelfWidget;
@@ -114,8 +113,6 @@ class ASH_EXPORT RootWindowController : public ShellObserver {
   aura::Window* GetRootWindow();
   const aura::Window* GetRootWindow() const;
 
-  RootWindowLayoutManager* root_window_layout() { return root_window_layout_; }
-
   WorkspaceController* workspace_controller() {
     return workspace_controller_.get();
   }
@@ -275,8 +272,6 @@ class ASH_EXPORT RootWindowController : public ShellObserver {
 
   std::unique_ptr<RootWindowControllerCommon> root_window_controller_common_;
 
-  RootWindowLayoutManager* root_window_layout_;
-
   std::unique_ptr<StackingController> stacking_controller_;
 
   // The shelf widget for this root window.