mus: Changes SetDisplayRoot() to create actual display

services/ui/service.h

Index: services/ui/service.h
diff --git a/services/ui/service.h b/services/ui/service.h
index 92e5f6078282a3680bd217cbe7214221b5345007..7bb947a8179a62d178770e241eae48e15d54bb4d 100644
--- a/services/ui/service.h
+++ b/services/ui/service.h
@@ -83,6 +83,20 @@ class Service
   ~Service() override;
 
  private:
+  // How the ScreenManager is configured.
+  enum ScreenManagerConfig {
+    // Initial state.
+    UNKNOWN,
+
+    // ScreenManager runs locally.
+    INTERNAL,
+
+    // Used when the window manager supplies a value of false for
+    // |automatically_create_display_roots|. In this config the ScreenManager
+    // is configured to forward calls.
+    FORWARDING,
+  };
+
   // Holds InterfaceRequests received before the first WindowTreeHost Display
   // has been established.
   struct PendingRequest;
@@ -111,6 +125,9 @@ class Service
   void OnFirstDisplayReady() override;
   void OnNoMoreDisplays() override;
   bool IsTestConfig() const override;
+  void OnWillCreateTreeForWindowManager(
+      bool automatically_create_display_roots) override;
+  display::ScreenBase* GetScreen() override;
 
   // service_manager::InterfaceFactory<mojom::AccessibilityManager>
   // implementation.
@@ -198,6 +215,11 @@ class Service
 
   service_manager::BinderRegistry registry_;
 
+  // Set to true in StartDisplayInit().
+  bool is_gpu_ready_ = false;
+  ScreenManagerConfig screen_manager_config_ = ScreenManagerConfig::UNKNOWN;
+  std::unique_ptr<display::ScreenBase> screen_;

[kylechar, 2017/04/19 18:06:08]

ScreenManagerOzoneInternal and ScreenManagerStubInternal both create a
ScreenBase instance already. I wonder if you could move this to
ScreenManagerForwarding and then add virtual ScreenManager::GetScreen()?
ScreenManager is already a singleton, so WindowServerDelegate::GetScreen()
wouldn't be necessary.

[sky, 2017/04/19 19:30:03]

Done.

+
   DISALLOW_COPY_AND_ASSIGN(Service);
 };