Refators display related functionality into own class

components/mus/ws/display_manager.h

Index: components/mus/ws/display_manager.h
diff --git a/components/mus/ws/display_manager.h b/components/mus/ws/display_manager.h
new file mode 100644
index 0000000000000000000000000000000000000000..7123469ad70979f4894353f6eb5eef68f499f46e
--- /dev/null
+++ b/components/mus/ws/display_manager.h
@@ -0,0 +1,90 @@
+// 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 COMPONENTS_MUS_WS_DISPLAY_MANAGER_H_
+#define COMPONENTS_MUS_WS_DISPLAY_MANAGER_H_
+
+#include <set>
+
+#include "base/macros.h"
+#include "components/mus/ws/ids.h"
+
+namespace mus {
+namespace ws {
+
+class Display;
+class DisplayManagerDelegate;
+class ServerWindow;
+class WindowManagerState;
+
+struct WindowManagerAndDisplay {
+  WindowManagerAndDisplay() : window_manager_state(nullptr), display(nullptr) {}
+
+  WindowManagerState* window_manager_state;
+  Display* display;
+};
+
+struct WindowManagerAndDisplayConst {
+  WindowManagerAndDisplayConst()
+      : window_manager_state(nullptr), display(nullptr) {}
+  const WindowManagerState* window_manager_state;
+  const Display* display;
+};
+
+class DisplayManager {
+ public:
+  explicit DisplayManager(DisplayManagerDelegate* delegate);
+  ~DisplayManager();
+
+  // Adds/removes a Display. DisplayManager owns the Displays.
+  // TODO(sky): make add take a scoped_ptr.
+  void AddDisplay(Display* display);
+  void DestroyDisplay(Display* display);
+  void DestroyAllDisplays();
+  const std::set<Display*>& displays() { return displays_; }
+  std::set<const Display*> displays() const;
+
+  // Returns the Display that contains |window|, or null if |window| is not
+  // attached to a display.
+  Display* GetDisplayContaining(ServerWindow* window);
+  const Display* GetDisplayContaining(const ServerWindow* window) const;
+
+  Display* GetActiveDisplay();
+
+  WindowManagerAndDisplayConst GetWindowManagerAndDisplay(
+      const ServerWindow* window) const;
+  WindowManagerAndDisplay GetWindowManagerAndDisplay(
+      const ServerWindow* window);
+
+  bool has_displays() const { return !displays_.empty(); }
+  bool has_active_or_pending_displays() const {
+    return !displays_.empty() || !pending_displays_.empty();
+  }
+
+  // Returns the id for the next root window (both for the root of a Display
+  // as well as the root of WindowManagers).
+  WindowId GetAndAdvanceNextRootId();
+
+  // Called when the AcceleratedWidget is available for |display|.
+  void OnDisplayAcceleratedWidgetAvailable(Display* display);
+
+ private:
+  DisplayManagerDelegate* delegate_;
+
+  // Displays are initially added to |pending_displays_|. When the display is
+  // initialized it is moved to |displays_|. ConnectionManager owns the
+  // Displays.
+  std::set<Display*> pending_displays_;
+  std::set<Display*> displays_;
+
+  // ID to use for next root node.
+  ConnectionSpecificId next_root_id_;
+
+  DISALLOW_COPY_AND_ASSIGN(DisplayManager);
+};
+
+}  // namespace ws
+}  // namespace mus
+
+#endif  // COMPONENTS_MUS_WS_DISPLAY_MANAGER_H_