chromeos: Changes DisplayManagerObserver to have a single function

services/ui/ws/user_display_manager.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 SERVICES_UI_WS_USER_DISPLAY_MANAGER_H_
 #define SERVICES_UI_WS_USER_DISPLAY_MANAGER_H_
 
 #include <vector>
 
 #include "base/macros.h"
@@ skipping 18 matching lines @@
                      const UserId& user_id);
   ~UserDisplayManager() override;
 
   // Called when the frame decorations for this user change.
   void OnFrameDecorationValuesChanged();
 
   void AddDisplayManagerBinding(
       mojo::InterfaceRequest<mojom::DisplayManager> request);
 
   // Called when something about the display (e.g. pixel-ratio, size) changes.
-  void OnDisplayUpdate(const display::Display& display);
+  void OnDisplayUpdated(const display::Display& display);
 
-  // Called when |display_id| is being removed.
-  void OnWillDestroyDisplay(int64_t display_id);
+  // Called when the display with |display_id| was removed.
+  void OnDisplayDestroyed(int64_t display_id);
 
   // Called when the primary display changes.
   void OnPrimaryDisplayChanged(int64_t primary_display_id);
 
   // Overriden from mojom::DisplayManager:
   void AddObserver(mojom::DisplayManagerObserverPtr observer) override;
 
  private:
   // Called when a new observer is added. If frame decorations are available
   // notifies the observer immediately.
   void OnObserverAdded(mojom::DisplayManagerObserver* observer);
 
   // Fills in a WsDisplayPtr for |display|.
   mojom::WsDisplayPtr ToWsDisplayPtr(const display::Display& display);
 
   std::vector<mojom::WsDisplayPtr> GetAllDisplays();
 
-  // Calls OnDisplays() on |observer|.
-  void CallOnDisplays(mojom::DisplayManagerObserver* observer);
+  bool ShouldCallOnDisplaysChanged() const;
+
+  // Calls OnDisplaysChanged() on all observers.
+  void CallOnDisplaysChangedIfNecessary();
+
+  // Calls OnDisplaysChanged() on |observer|.
+  void CallOnDisplaysChanged(mojom::DisplayManagerObserver* observer);
 
   UserDisplayManagerDelegate* delegate_;
 
   const UserId user_id_;
 
   // Set to true the first time at least one Display has valid frame values.
   bool got_valid_frame_decorations_;
 
   mojo::BindingSet<mojom::DisplayManager> display_manager_bindings_;
 
   // WARNING: only use these once |got_valid_frame_decorations_| is true.
   mojo::InterfacePtrSet<mojom::DisplayManagerObserver>
       display_manager_observers_;
 
   DISALLOW_COPY_AND_ASSIGN(UserDisplayManager);
 };
 
 }  // namespace ws
 }  // namespace ui
 
 #endif  // SERVICES_UI_WS_USER_DISPLAY_MANAGER_H_