Allow dynamic enabling/disabling of unified desktop

ash/system/chromeos/tray_display_unittest.cc

 // Copyright 2013 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/system/chromeos/tray_display.h"
 
 #include "ash/display/display_manager.h"
 #include "ash/root_window_controller.h"
 #include "ash/screen_util.h"
 #include "ash/shell.h"
@@ skipping 297 matching lines @@
   EXPECT_TRUE(IsDisplayVisibleInTray());
   expected = l10n_util::GetStringUTF16(IDS_ASH_STATUS_TRAY_DISPLAY_DOCKED);
   EXPECT_EQ(expected, GetTrayDisplayText());
   EXPECT_EQ(
       GetTooltipText(
           expected, GetFirstDisplayName(), "600x600", base::string16(), ""),
       GetTrayDisplayTooltipText());
   CheckAccessibleName();
 
   // Unified mode
-  test::DisplayManagerTestApi::EnableUnifiedDesktopForTest();
-  display_manager->SetDefaultMultiDisplayMode(DisplayManager::UNIFIED);
-  display_manager->SetMultiDisplayMode(DisplayManager::UNIFIED);
+  display_manager->SetUnifiedDesktopEnabled(true);
   UpdateDisplay("300x200,400x500");
   // Update the cache variables as the primary root window changed.
   GetTray()->ShowDefaultView(BUBBLE_USE_EXISTING);
   EXPECT_TRUE(IsDisplayVisibleInTray());
   expected = l10n_util::GetStringUTF16(IDS_ASH_STATUS_TRAY_DISPLAY_UNIFIED);
   EXPECT_EQ(expected, GetTrayDisplayText());
 }
 
 TEST_F(TrayDisplayTest, ExternalDisplayResized) {
   UpdateDisplay("400x400");
@@ skipping 260 matching lines @@
   // rotate the second.
   UpdateDisplay("400x400,200x200/r");
   EXPECT_EQ(l10n_util::GetStringFUTF16(
                 IDS_ASH_STATUS_TRAY_DISPLAY_ROTATED, GetSecondDisplayName(),
                 l10n_util::GetStringUTF16(
                     IDS_ASH_STATUS_TRAY_DISPLAY_ORIENTATION_90)),
             GetDisplayNotificationAdditionalText());
 }
 
 }  // namespace ash