Only enable mirroring for 2 displays

chrome/browser/ui/webui/options/chromeos/display_options_handler.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 "chrome/browser/ui/webui/options/chromeos/display_options_handler.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <string>
@@ skipping 340 matching lines @@
     }
 
     js_displays->Append(js_display);
   }
 
   web_ui()->CallJavascriptFunction("options.DisplayOptions.setDisplayInfo",
                                    mode, *js_displays);
 }
 
 void DisplayOptionsHandler::UpdateDisplaySettingsEnabled() {
+  ash::DisplayManager* display_manager = GetDisplayManager();
   bool disable_multi_display_layout =
       base::CommandLine::ForCurrentProcess()->HasSwitch(
           chromeos::switches::kDisableMultiDisplayLayout);
-  bool enabled = !(disable_multi_display_layout &&
-                   GetDisplayManager()->num_connected_displays() > 2);
-  bool show_unified_desktop = GetDisplayManager()->unified_desktop_enabled();
+  bool ui_enabled = display_manager->num_connected_displays() <= 2 ||
+                    !disable_multi_display_layout;
+  bool unified_enabled = display_manager->unified_desktop_enabled();
+  bool mirrored_enabled = display_manager->num_connected_displays() == 2;
 
   web_ui()->CallJavascriptFunction(
       "options.BrowserOptions.enableDisplaySettings",
-      base::FundamentalValue(enabled),
-      base::FundamentalValue(show_unified_desktop));
+      base::FundamentalValue(ui_enabled),
+      base::FundamentalValue(unified_enabled),
+      base::FundamentalValue(mirrored_enabled));
 }
 
 void DisplayOptionsHandler::HandleDisplayInfo(
     const base::ListValue* unused_args) {
   SendAllDisplayInfo();
 }
 
 void DisplayOptionsHandler::HandleMirroring(const base::ListValue* args) {
   DCHECK(!args->empty());
   bool is_mirroring = false;
@@ skipping 168 matching lines @@
   bool enable = false;
   if (!args->GetBoolean(0, &enable))
     NOTREACHED();
 
   GetDisplayManager()->SetDefaultMultiDisplayModeForCurrentDisplays(
       enable ? ash::DisplayManager::UNIFIED : ash::DisplayManager::EXTENDED);
 }
 
 }  // namespace options
 }  // namespace chromeos