Primary display change notifications.

services/ui/ws/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/display_manager.h"
 
 #include "base/memory/ptr_util.h"
 #include "base/trace_event/trace_event.h"
 #include "services/ui/display/platform_screen.h"
 #include "services/ui/ws/display.h"
@@ skipping 196 matching lines @@
       window_server_->window_manager_window_tree_factory_set()->GetFactories();
   for (WindowManagerWindowTreeFactory* factory : factories) {
     if (factory->window_tree())
       factory->window_tree()->OnWmDisplayModified(display->ToDisplay());
   }
 
   display->OnViewportMetricsChanged(metrics);
   OnDisplayUpdate(display);
 }
 
+void DisplayManager::OnPrimaryDisplayChanged(int64_t primary_display_id) {
+  // TODO(kylechar): Send IPCs to WM clients first.
+
+  // Send IPCs to any DisplayManagerObservers.
+  for (const auto& pair : user_display_managers_)
+    pair.second->OnPrimaryDisplayChanged(primary_display_id);
+}
+
 }  // namespace ws
 }  // namespace ui