[Cleanup] Factor out layout store code from DisplayController

ash/display/display_controller_unittest.cc

Index: ash/display/display_controller_unittest.cc
diff --git a/ash/display/display_controller_unittest.cc b/ash/display/display_controller_unittest.cc
index d126c9858f5156d6b738ad7ed842d29a1698f817..74be2b0b600c49c1c006013cb6464efa9ef9dfdf 100644
--- a/ash/display/display_controller_unittest.cc
+++ b/ash/display/display_controller_unittest.cc
@@ -5,6 +5,7 @@
 #include "ash/display/display_controller.h"
 
 #include "ash/display/display_info.h"
+#include "ash/display/display_layout_store.h"
 #include "ash/display/display_manager.h"
 #include "ash/launcher/launcher.h"
 #include "ash/screen_ash.h"
@@ -77,11 +78,10 @@ gfx::Display GetSecondaryDisplay() {
 
 void SetSecondaryDisplayLayoutAndOffset(DisplayLayout::Position position,
                                         int offset) {
-  DisplayController* display_controller =
-      Shell::GetInstance()->display_controller();
   DisplayLayout layout(position, offset);
   ASSERT_GT(Shell::GetScreen()->GetNumDisplays(), 1);
-  display_controller->SetLayoutForCurrentDisplays(layout);
+  Shell::GetInstance()->display_controller()->
+      SetLayoutForCurrentDisplays(layout);
 }
 
 void SetSecondaryDisplayLayout(DisplayLayout::Position position) {
@@ -89,7 +89,7 @@ void SetSecondaryDisplayLayout(DisplayLayout::Position position) {
 }
 
 void SetDefaultDisplayLayout(DisplayLayout::Position position) {
-  Shell::GetInstance()->display_controller()->
+  Shell::GetInstance()->display_manager()->layout_store()->
       SetDefaultDisplayLayout(DisplayLayout(position, 0));
 }