Revert of Save and restore unified mode

ash/display/display_manager_unittest.cc

Index: ash/display/display_manager_unittest.cc
diff --git a/ash/display/display_manager_unittest.cc b/ash/display/display_manager_unittest.cc
index 3e9809d166bd1c4d9eda0e4855d94319f9f2bc5b..d9dda9e760a343652cdca99f1d93c633ceecd1a5 100644
--- a/ash/display/display_manager_unittest.cc
+++ b/ash/display/display_manager_unittest.cc
@@ -1463,8 +1463,6 @@
 TEST_F(DisplayManagerTest, UnifiedDesktopBasic) {
   if (!SupportsMultipleDisplays())
     return;
-  test::DisplayManagerTestApi::EnableUnifiedDesktopForTest();
-
   // Don't check root window destruction in unified mode.
   Shell::GetPrimaryRootWindow()->RemoveObserver(this);
 
@@ -1502,8 +1500,6 @@
 TEST_F(DisplayManagerTest, RotateUnifiedDesktop) {
   if (!SupportsMultipleDisplays())
     return;
-  test::DisplayManagerTestApi::EnableUnifiedDesktopForTest();
-
   // Don't check root window destruction in unified mode.
   Shell::GetPrimaryRootWindow()->RemoveObserver(this);
 
@@ -1531,8 +1527,6 @@
 TEST_F(DisplayManagerTest, UnifiedWithDockWindows) {
   if (!SupportsMultipleDisplays())
     return;
-  test::DisplayManagerTestApi::EnableUnifiedDesktopForTest();
-
   // Don't check root window destruction in unified mode.
   Shell::GetPrimaryRootWindow()->RemoveObserver(this);