Allow dynamic enabling/disabling of unified desktop

ash/display/display_layout.cc

Index: ash/display/display_layout.cc
diff --git a/ash/display/display_layout.cc b/ash/display/display_layout.cc
index 2cf54a6f2d51e41400d26e1c0e740d829128b963..9816f21b694d54909c03da804e908d282f6150f7 100644
--- a/ash/display/display_layout.cc
+++ b/ash/display/display_layout.cc
@@ -5,7 +5,9 @@
 #include "ash/display/display_layout.h"
 
 #include "ash/ash_switches.h"
+#include "ash/display/display_manager.h"
 #include "ash/display/display_pref_util.h"
+#include "ash/shell.h"
 #include "base/json/json_value_converter.h"
 #include "base/logging.h"
 #include "base/strings/string_number_conversions.h"
@@ -72,7 +74,7 @@ DisplayLayout::DisplayLayout()
       offset(0),
       mirrored(false),
 #if defined(OS_CHROMEOS)
-      default_unified(switches::UnifiedDesktopEnabled()),
+      default_unified(true),
 #else
       default_unified(false),
 #endif
@@ -84,7 +86,7 @@ DisplayLayout::DisplayLayout(DisplayLayout::Position position, int offset)
       offset(offset),
       mirrored(false),
 #if defined(OS_CHROMEOS)
-      default_unified(switches::UnifiedDesktopEnabled()),
+      default_unified(true),
 #else
       default_unified(false),
 #endif
@@ -146,9 +148,13 @@ bool DisplayLayout::ConvertToValue(const DisplayLayout& layout,
 
 std::string DisplayLayout::ToString() const {
   const std::string position_str = GetStringFromPosition(position);
+  bool unified =
+      default_unified &&
+      Shell::GetInstance()->display_manager()->unified_desktop_enabled();
+
   return base::StringPrintf("%s, %d%s%s", position_str.c_str(), offset,
                             mirrored ? ", mirrored" : "",
-                            default_unified ? ", unified" : "");
+                            unified ? ", unified" : "");
 }
 
 // static