Change single-display screens to use ScreenBase and DisplayList.

ui/views/mus/screen_mus.cc

Index: ui/views/mus/screen_mus.cc
diff --git a/ui/views/mus/screen_mus.cc b/ui/views/mus/screen_mus.cc
index a7a05ba227598469e204bf3de8bdb9d52cda1090..d6fbbd74494bcc7d7b4c8b2307a913a4bc8d0243 100644
--- a/ui/views/mus/screen_mus.cc
+++ b/ui/views/mus/screen_mus.cc
@@ -37,9 +37,14 @@ namespace views {
 using Type = display::DisplayList::Type;
 
 ScreenMus::ScreenMus(ScreenMusDelegate* delegate)
-    : delegate_(delegate), display_manager_observer_binding_(this) {}
+    : delegate_(delegate), display_manager_observer_binding_(this) {
+  display::Screen::SetScreenInstance(this);
+}
 
-ScreenMus::~ScreenMus() {}
+ScreenMus::~ScreenMus() {
+  DCHECK_EQ(this, display::Screen::GetScreen());
+  display::Screen::SetScreenInstance(nullptr);
+}
 
 void ScreenMus::Init(service_manager::Connector* connector) {
   connector->ConnectToInterface("service:ui", &display_manager_);
@@ -56,11 +61,11 @@ void ScreenMus::Init(service_manager::Connector* connector) {
   // The WaitForIncomingMethodCall() should have supplied the set of Displays,
   // unless mus is going down, in which case encountered_error() is true, or the
   // call to WaitForIncomingMethodCall() failed.
-  if (display_list()->displays().empty()) {
+  if (display_list().displays().empty()) {
     DCHECK(display_manager_.encountered_error() || !success);
     // In this case we install a default display and assume the process is
     // going to exit shortly so that the real value doesn't matter.
-    display_list()->AddDisplay(
+    display_list().AddDisplay(
         display::Display(0xFFFFFFFF, gfx::Rect(0, 0, 801, 802)), Type::PRIMARY);
   }
 }
@@ -89,13 +94,13 @@ void ScreenMus::OnDisplays(mojo::Array<ui::mojom::WsDisplayPtr> ws_displays,
                            int64_t primary_display_id,
                            int64_t internal_display_id) {
   // This should only be called once when ScreenMus is added as an observer.
-  DCHECK(display_list()->displays().empty());
+  DCHECK(display_list().displays().empty());
 
   for (size_t i = 0; i < ws_displays.size(); ++i) {
     const display::Display& display = ws_displays[i]->display;
     const bool is_primary = display.id() == primary_display_id;
-    display_list()->AddDisplay(display,
-                               is_primary ? Type::PRIMARY : Type::NOT_PRIMARY);
+    display_list().AddDisplay(display,
+                              is_primary ? Type::PRIMARY : Type::NOT_PRIMARY);
     if (is_primary) {
       // TODO(sky): Make WindowManagerFrameValues per display.
       WindowManagerFrameValues frame_values =
@@ -105,13 +110,13 @@ void ScreenMus::OnDisplays(mojo::Array<ui::mojom::WsDisplayPtr> ws_displays,
     }
   }
 
-  DCHECK(display_list()->GetPrimaryDisplayIterator() !=
-         display_list()->displays().end());
+  DCHECK(display_list().GetPrimaryDisplayIterator() !=
+         display_list().displays().end());
 
   if (internal_display_id != display::Display::kInvalidDisplayID)
     display::Display::SetInternalDisplayId(internal_display_id);
 
-  DCHECK(!display_list()->displays().empty());
+  DCHECK(!display_list().displays().empty());
 }
 
 void ScreenMus::OnDisplaysChanged(
@@ -119,7 +124,7 @@ void ScreenMus::OnDisplaysChanged(
   for (size_t i = 0; i < ws_displays.size(); ++i) {
     const display::Display& display = ws_displays[i]->display;
     const bool is_primary =
-        display.id() == display_list()->GetPrimaryDisplayIterator()->id();
+        display.id() == display_list().GetPrimaryDisplayIterator()->id();
     ProcessDisplayChanged(display, is_primary);
     if (is_primary) {
       WindowManagerFrameValues frame_values =
@@ -133,7 +138,7 @@ void ScreenMus::OnDisplaysChanged(
 }
 
 void ScreenMus::OnDisplayRemoved(int64_t display_id) {
-  display_list()->RemoveDisplay(display_id);
+  display_list().RemoveDisplay(display_id);
 }
 
 void ScreenMus::OnPrimaryDisplayChanged(int64_t primary_display_id) {
@@ -142,7 +147,7 @@ void ScreenMus::OnPrimaryDisplayChanged(int64_t primary_display_id) {
   if (primary_display_id == display::Display::kInvalidDisplayID)
     return;
 
-  ProcessDisplayChanged(*display_list()->FindDisplayById(primary_display_id),
+  ProcessDisplayChanged(*display_list().FindDisplayById(primary_display_id),
                         true);
 }