Use list instead of pair to represent the set of displays.

ash/display/window_tree_host_manager.cc

 // Copyright (c) 2012 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 "ash/display/window_tree_host_manager.h"
 
 #include <algorithm>
 #include <cmath>
 #include <map>
 #include <utility>
@@ skipping 433 matching lines @@
   window_tree_hosts_[new_primary_display.id()] = primary_host;
   GetRootWindowSettings(GetWindow(primary_host))->display_id =
       new_primary_display.id();
 
   window_tree_hosts_[old_primary_display.id()] = non_primary_host;
   GetRootWindowSettings(GetWindow(non_primary_host))->display_id =
       old_primary_display.id();
 
   primary_display_id = new_primary_display.id();
   GetDisplayManager()->layout_store()->UpdatePrimaryDisplayId(
-      display_manager->GetCurrentDisplayIdPair(), primary_display_id);
+      display_manager->GetCurrentDisplayIdList(), primary_display_id);
 
   UpdateWorkAreaOfDisplayNearestWindow(GetWindow(primary_host),
                                        old_primary_display.GetWorkAreaInsets());
   UpdateWorkAreaOfDisplayNearestWindow(GetWindow(non_primary_host),
                                        new_primary_display.GetWorkAreaInsets());
 
   // Update the dispay manager with new display info.
   GetDisplayManager()->set_force_bounds_changed(true);
   GetDisplayManager()->UpdateDisplays();
   GetDisplayManager()->set_force_bounds_changed(false);
@@ skipping 291 matching lines @@
   root_window->GetHost()->ConvertPointToNativeScreen(&point_in_native);
   cursor_location_in_native_coords_for_restore_ = point_in_native;
 }
 
 void WindowTreeHostManager::PostDisplayConfigurationChange() {
   focus_activation_store_->Restore();
 
   DisplayManager* display_manager = GetDisplayManager();
   DisplayLayoutStore* layout_store = display_manager->layout_store();
   if (display_manager->num_connected_displays() > 1) {
-    DisplayIdPair pair = display_manager->GetCurrentDisplayIdPair();
-    DisplayLayout layout = layout_store->GetRegisteredDisplayLayout(pair);
+    DisplayIdList list = display_manager->GetCurrentDisplayIdList();
+    DisplayLayout layout = layout_store->GetRegisteredDisplayLayout(list);
     layout_store->UpdateMultiDisplayState(
-        pair, display_manager->IsInMirrorMode(), layout.default_unified);
+        list, display_manager->IsInMirrorMode(), layout.default_unified);
 
     if (gfx::Screen::GetScreen()->GetNumDisplays() > 1) {
       int64_t primary_id = layout.primary_id;
-      SetPrimaryDisplayId(primary_id == gfx::Display::kInvalidDisplayID
-                              ? pair.first
-                              : primary_id);
+      SetPrimaryDisplayId(
+          primary_id == gfx::Display::kInvalidDisplayID ? list[0] : primary_id);
       // Update the primary_id in case the above call is
       // ignored. Happens when a) default layout's primary id
       // doesn't exist, or b) the primary_id has already been
       // set to the same and didn't update it.
       layout_store->UpdatePrimaryDisplayId(
-          pair, gfx::Screen::GetScreen()->GetPrimaryDisplay().id());
+          list, gfx::Screen::GetScreen()->GetPrimaryDisplay().id());
     }
   }
   FOR_EACH_OBSERVER(Observer, observers_, OnDisplayConfigurationChanged());
   UpdateMouseLocationAfterDisplayChange();
 }
 
 ui::EventDispatchDetails WindowTreeHostManager::DispatchKeyEventPostIME(
     ui::KeyEvent* event) {
   // Getting the active root window to dispatch the event. This isn't
   // significant as the event will be sent to the window resolved by
@@ skipping 43 matching lines @@
   SetDisplayPropertiesOnHost(ash_host, display);
 
 #if defined(OS_CHROMEOS)
   if (switches::ConstrainPointerToRoot())
     ash_host->ConfineCursorToRootWindow();
 #endif
   return ash_host;
 }
 
 }  // namespace ash