Move DisplayList to display; add ScreenBase.

ash/mus/test/wm_test_screen.h

Index: ash/mus/test/wm_test_screen.h
diff --git a/ash/mus/test/wm_test_screen.h b/ash/mus/test/wm_test_screen.h
index 4545804432cde15ca228e7a0671d05aed92744cc..dd28b3a06c99a05b8d3675ef6f464929e9ee830a 100644
--- a/ash/mus/test/wm_test_screen.h
+++ b/ash/mus/test/wm_test_screen.h
@@ -5,39 +5,22 @@
 #ifndef ASH_MUS_TEST_WM_TEST_SCREEN_H_
 #define ASH_MUS_TEST_WM_TEST_SCREEN_H_
 
-#include "ui/display/screen.h"
-#include "ui/views/mus/display_list.h"
+#include "ui/display/screen_base.h"
 
 namespace ash {
 namespace mus {
 
 // Screen implementation used by tests for the windowmanager. Does not talk
 // to mus. Tests must keep the list of Displays in sync manually.
-class WmTestScreen : public display::Screen {
+class WmTestScreen : public display::ScreenBase {
  public:
   WmTestScreen();
   ~WmTestScreen() override;
 
-  const views::DisplayList& display_list() const { return display_list_; }
-  views::DisplayList* display_list() { return &display_list_; }
-
  private:
-  // display::Screen:
+  // display::ScreenBase:
   gfx::Point GetCursorScreenPoint() override;
   bool IsWindowUnderCursor(gfx::NativeWindow window) override;
-  gfx::NativeWindow GetWindowAtScreenPoint(const gfx::Point& point) override;
-  display::Display GetPrimaryDisplay() const override;
-  display::Display GetDisplayNearestWindow(gfx::NativeView view) const override;
-  display::Display GetDisplayNearestPoint(
-      const gfx::Point& point) const override;
-  int GetNumDisplays() const override;
-  std::vector<display::Display> GetAllDisplays() const override;
-  display::Display GetDisplayMatching(
-      const gfx::Rect& match_rect) const override;
-  void AddObserver(display::DisplayObserver* observer) override;
-  void RemoveObserver(display::DisplayObserver* observer) override;
-
-  views::DisplayList display_list_;
 
   DISALLOW_COPY_AND_ASSIGN(WmTestScreen);
 };