[Extensions] Make Event::restrict_to_browser_context const.

chrome/browser/extensions/api/tab_capture/tab_capture_registry.cc

Index: chrome/browser/extensions/api/tab_capture/tab_capture_registry.cc
diff --git a/chrome/browser/extensions/api/tab_capture/tab_capture_registry.cc b/chrome/browser/extensions/api/tab_capture/tab_capture_registry.cc
index c1fe19aeaf45297be07fa5cf09ba526270c7952d..3e096dfdd738c34aa46c25d7f5a3bb1eaab23b46 100644
--- a/chrome/browser/extensions/api/tab_capture/tab_capture_registry.cc
+++ b/chrome/browser/extensions/api/tab_capture/tab_capture_registry.cc
@@ -427,10 +427,9 @@ void TabCaptureRegistry::DispatchStatusChangeEvent(
   tab_capture::CaptureInfo info;
   request->GetCaptureInfo(&info);
   args->Append(info.ToValue());
-  std::unique_ptr<Event> event(
-      new Event(events::TAB_CAPTURE_ON_STATUS_CHANGED,
-                tab_capture::OnStatusChanged::kEventName, std::move(args)));
-  event->restrict_to_browser_context = browser_context_;
+  auto event = base::MakeUnique<Event>(events::TAB_CAPTURE_ON_STATUS_CHANGED,
+                                       tab_capture::OnStatusChanged::kEventName,
+                                       std::move(args), browser_context_);
 
   router->DispatchEventToExtension(request->extension_id(), std::move(event));
 }