chromeos: changes how DisplayManagerObservers are notified

services/ui/ws/user_display_manager.cc

 // 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.
 
 #include "services/ui/ws/user_display_manager.h"
 
 #include <utility>
 
 #include "services/ui/ws/user_display_manager_delegate.h"
 #include "ui/display/display.h"
@@ skipping 15 matching lines @@
 
 UserDisplayManager::UserDisplayManager(UserDisplayManagerDelegate* delegate,
                                        const UserId& user_id)
     : delegate_(delegate),
       user_id_(user_id),
       got_valid_frame_decorations_(
           delegate->GetFrameDecorationsForUser(user_id, nullptr)) {}
 
 UserDisplayManager::~UserDisplayManager() {}
 
+void UserDisplayManager::DisableAutomaticNotification() {
+  DCHECK(notify_automatically_);
+  notify_automatically_ = false;
+}
+
+void UserDisplayManager::CallOnDisplaysChanged() {
+  display_manager_observers_.ForAllPtrs(
+      [this](mojom::DisplayManagerObserver* observer) {
+        CallOnDisplaysChanged(observer);
+      });
+}
+
 void UserDisplayManager::OnFrameDecorationValuesChanged() {
   got_valid_frame_decorations_ = true;
   CallOnDisplaysChangedIfNecessary();
 }
 
 void UserDisplayManager::AddDisplayManagerBinding(
     mojo::InterfaceRequest<mojom::DisplayManager> request) {
   display_manager_bindings_.AddBinding(this, std::move(request));
 }
 
@@ skipping 47 matching lines @@
 
   return ws_display;
 }
 
 bool UserDisplayManager::ShouldCallOnDisplaysChanged() const {
   return got_valid_frame_decorations_ &&
          !display::Screen::GetScreen()->GetAllDisplays().empty();
 }
 
 void UserDisplayManager::CallOnDisplaysChangedIfNecessary() {
-  if (!ShouldCallOnDisplaysChanged())
+  if (!notify_automatically_ || !ShouldCallOnDisplaysChanged())
     return;
 
-  display_manager_observers_.ForAllPtrs(
-      [this](mojom::DisplayManagerObserver* observer) {
-        CallOnDisplaysChanged(observer);
-      });
+  CallOnDisplaysChanged();
 }
 
 void UserDisplayManager::CallOnDisplaysChanged(
     mojom::DisplayManagerObserver* observer) {
   observer->OnDisplaysChanged(
       GetAllDisplays(), display::Screen::GetScreen()->GetPrimaryDisplay().id(),
       GetInternalDisplayId());
 }
 
 }  // namespace ws
 }  // namespace ui