Make ForwardingDisplayDelegate initially sync.

ui/display/manager/forwarding_display_delegate.h

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_DISPLAY_MANAGER_FORWARDING_DISPLAY_DELEGATE_H_
 #define UI_DISPLAY_MANAGER_FORWARDING_DISPLAY_DELEGATE_H_
 
 #include <memory>
 #include <vector>
 
@@ skipping 51 matching lines @@
                           const std::vector<GammaRampRGBEntry>& gamma_lut,
                           const std::vector<float>& correction_matrix) override;
   void AddObserver(display::NativeDisplayObserver* observer) override;
   void RemoveObserver(display::NativeDisplayObserver* observer) override;
   FakeDisplayController* GetFakeDisplayController() override;
 
   // display::mojom::NativeDisplayObserver:
   void OnConfigurationChanged() override;
 
  private:
-  // Stores display snapshots and forards them to |callback|.
+  // Stores display snapshots and forwards pointers to |callback|.
   void StoreAndForwardDisplays(
       const GetDisplaysCallback& callback,
       std::vector<std::unique_ptr<DisplaySnapshotMojo>> snapshots);
 
+  // Forwards display snapshot pointers to |callback|.
+  void ForwardDisplays(const GetDisplaysCallback& callback);
+
+  // True if we should use |delegate_|. This will be false if synchronous
+  // GetDisplays() and Configure() are required.
+  bool use_delegate_ = false;
+
   mojom::NativeDisplayDelegatePtr delegate_;
   mojo::Binding<mojom::NativeDisplayObserver> binding_;
 
   // Display snapshots are owned here but accessed via raw pointers elsewhere.
   // Call OnDisplaySnapshotsInvalidated() on observers before invalidating them.
   std::vector<std::unique_ptr<DisplaySnapshotMojo>> snapshots_;
 
   base::ObserverList<display::NativeDisplayObserver> observers_;
 
   DISALLOW_COPY_AND_ASSIGN(ForwardingDisplayDelegate);
 };
 
 }  // namespace display
 
 #endif  // UI_DISPLAY_MANAGER_FORWARDING_DISPLAY_DELEGATE_H_