2nd display should show the same background as login/lock screen:

ash/wm/root_window_layout_manager.cc

Index: ash/wm/root_window_layout_manager.cc
diff --git a/ash/wm/root_window_layout_manager.cc b/ash/wm/root_window_layout_manager.cc
index 52c117e322a3f4b6285eef05326575ce8eb635f2..f64b4545656c7aa53005ee7fbdacc3ce03687c50 100644
--- a/ash/wm/root_window_layout_manager.cc
+++ b/ash/wm/root_window_layout_manager.cc
@@ -15,24 +15,32 @@ namespace internal {
 // RootWindowLayoutManager, public:
 
 RootWindowLayoutManager::RootWindowLayoutManager(aura::Window* owner)
-    : owner_(owner),
-      background_widget_(NULL) {
+    : owner_(owner) {
+  for (int i = 0; i < kShellWindowCount; i++)
+    background_widget_[i] = NULL;
 }
 
 RootWindowLayoutManager::~RootWindowLayoutManager() {
 }
 
-void RootWindowLayoutManager::SetBackgroundWidget(views::Widget* widget) {
-  if (widget == background_widget_)
+void RootWindowLayoutManager::SetBackgroundWidget(views::Widget* widget,
+    int container_id) {
+  if (widget == background_widget_[container_id])
     return;
   // Close now so that the focus manager will be deleted before shutdown.
-  if (background_widget_)
-    background_widget_->CloseNow();
-  background_widget_ = widget;
+  if (background_widget_[container_id])
+    background_widget_[container_id]->CloseNow();
+  background_widget_[container_id] = widget;
 }
 
-void RootWindowLayoutManager::SetBackgroundLayer(ui::Layer* layer) {
-  background_layer_.reset(layer);
+void RootWindowLayoutManager::SetBackgroundLayer(ui::Layer* layer,
+    int container_id) {
+  background_layer_[container_id].reset(layer);
+}
+
+void RootWindowLayoutManager::DropBackgroundForContainer(int container_id) {
+  SetBackgroundLayer(NULL, container_id);
+  SetBackgroundWidget(NULL, container_id);
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -51,11 +59,12 @@ void RootWindowLayoutManager::OnWindowResized() {
     for (j = (*i)->children().begin(); j != (*i)->children().end(); ++j)
       (*j)->SetBounds(fullscreen_bounds);
   }
-
-  if (background_widget_)
-    background_widget_->SetBounds(fullscreen_bounds);
-  if (background_layer_.get())
-    background_layer_->SetBounds(fullscreen_bounds);
+  for (int i = 0; i < kShellWindowCount; i++) {
+    if (background_widget_[i])
+      background_widget_[i]->SetBounds(fullscreen_bounds);
+    if (background_layer_[i].get())
+      background_layer_[i]->SetBounds(fullscreen_bounds);
+  }
 }
 
 void RootWindowLayoutManager::OnWindowAddedToLayout(aura::Window* child) {