[Extensions] Make Event::restrict_to_browser_context const.

chrome/browser/extensions/api/sync_file_system/extension_sync_event_observer.cc

 // Copyright (c) 2012 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.
 
 #include "chrome/browser/extensions/api/sync_file_system/extension_sync_event_observer.h"
 
 #include <utility>
 
 #include "base/lazy_instance.h"
+#include "base/memory/ptr_util.h"
 #include "chrome/browser/extensions/api/sync_file_system/sync_file_system_api_helpers.h"
 #include "chrome/browser/sync_file_system/sync_event_observer.h"
 #include "chrome/browser/sync_file_system/sync_file_system_service.h"
 #include "chrome/browser/sync_file_system/sync_file_system_service_factory.h"
 #include "chrome/browser/sync_file_system/syncable_file_system_util.h"
 #include "chrome/common/extensions/api/sync_file_system.h"
 #include "content/public/browser/browser_context.h"
 #include "extensions/browser/event_router.h"
 #include "extensions/browser/extension_registry.h"
 #include "extensions/browser/extension_system_provider.h"
@@ skipping 101 matching lines @@
     const GURL& app_origin,
     events::HistogramValue histogram_value,
     const std::string& event_name,
     std::unique_ptr<base::ListValue> values) {
   // Check to see whether the event should be broadcasted to all listening
   // extensions or sent to a specific extension ID.
   bool broadcast_mode = app_origin.is_empty();
   EventRouter* event_router = EventRouter::Get(browser_context_);
   DCHECK(event_router);
 
-  std::unique_ptr<Event> event(
-      new Event(histogram_value, event_name, std::move(values)));
-  event->restrict_to_browser_context = browser_context_;
+  auto event = base::MakeUnique<Event>(histogram_value, event_name,
+                                       std::move(values), browser_context_);
 
   // No app_origin, broadcast to all listening extensions for this event name.
   if (broadcast_mode) {
     event_router->BroadcastEvent(std::move(event));
     return;
   }
 
   // Dispatch to single extension ID.
   const std::string extension_id = GetExtensionId(app_origin);
   if (extension_id.empty())
     return;
   event_router->DispatchEventToExtension(extension_id, std::move(event));
 }
 
 template <>
 void BrowserContextKeyedAPIFactory<
     ExtensionSyncEventObserver>::DeclareFactoryDependencies() {
   DependsOn(sync_file_system::SyncFileSystemServiceFactory::GetInstance());
   DependsOn(ExtensionsBrowserClient::Get()->GetExtensionSystemFactory());
 }
 
 }  // namespace extensions