chromeos: Fix handling of null in NativeDisplayDelegate

services/ui/display/screen_manager_forwarding.cc

Index: services/ui/display/screen_manager_forwarding.cc
diff --git a/services/ui/display/screen_manager_forwarding.cc b/services/ui/display/screen_manager_forwarding.cc
index 284114d8e0f8d9822f37c6c1ca9cb8d7830f88b0..8953a3042bb6049b3d7e9596b32522c68854d68e 100644
--- a/services/ui/display/screen_manager_forwarding.cc
+++ b/services/ui/display/screen_manager_forwarding.cc
@@ -117,7 +117,7 @@ void ScreenManagerForwarding::GetDisplays(const GetDisplaysCallback& callback) {
 
 void ScreenManagerForwarding::Configure(
     int64_t display_id,
-    std::unique_ptr<display::DisplayMode> mode,
+    base::Optional<std::unique_ptr<display::DisplayMode>> mode,
     const gfx::Point& origin,
     const ConfigureCallback& callback) {
   DCHECK(native_display_delegate_);
@@ -130,7 +130,7 @@ void ScreenManagerForwarding::Configure(
   // We need a pointer to the mode in |snapshot|, not the equivalent mode we
   // received over Mojo.
   const DisplayMode* snapshot_mode =
-      GetCorrespondingMode(*snapshot, mode.get());
+      mode ? GetCorrespondingMode(*snapshot, mode->get()) : nullptr;
   native_display_delegate_->Configure(
       *snapshot, snapshot_mode, origin,
       base::Bind(&ScreenManagerForwarding::ForwardConfigure,