Add initial support for native Linux desktop notifications

chrome/browser/notifications/notification_display_service_factory.cc

Index: chrome/browser/notifications/notification_display_service_factory.cc
diff --git a/chrome/browser/notifications/notification_display_service_factory.cc b/chrome/browser/notifications/notification_display_service_factory.cc
index 8b40bcdab31544c9e5c7c2a0f2df89c79634622f..3e7c4f17533e5000c53c894bbd2a78fa6578b7cd 100644
--- a/chrome/browser/notifications/notification_display_service_factory.cc
+++ b/chrome/browser/notifications/notification_display_service_factory.cc
@@ -12,9 +12,10 @@
 #include "chrome/browser/profiles/incognito_helpers.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/common/chrome_features.h"
+#include "chrome/common/features.h"
 #include "components/keyed_service/content/browser_context_dependency_manager.h"
 
-#if defined(OS_ANDROID) || defined(OS_MACOSX)
+#if BUILDFLAG(ENABLE_NATIVE_NOTIFICATIONS)
 #include "chrome/browser/notifications/native_notification_display_service.h"
 #endif
 
@@ -44,17 +45,20 @@ NotificationDisplayServiceFactory::NotificationDisplayServiceFactory()
 //   - All other platforms always use the MessageCenterDisplayService.
 KeyedService* NotificationDisplayServiceFactory::BuildServiceInstanceFor(
     content::BrowserContext* context) const {
+#if BUILDFLAG(ENABLE_NATIVE_NOTIFICATIONS)
 #if defined(OS_ANDROID)
   return new NativeNotificationDisplayService(
       Profile::FromBrowserContext(context),
       g_browser_process->notification_platform_bridge());
-#elif defined(OS_MACOSX)
-  if (base::FeatureList::IsEnabled(features::kNativeNotifications)) {
+#else   // defined(OS_ANDROID)
+  if (base::FeatureList::IsEnabled(features::kNativeNotifications) &&
+      g_browser_process->notification_platform_bridge()) {
     return new NativeNotificationDisplayService(
         Profile::FromBrowserContext(context),
         g_browser_process->notification_platform_bridge());
   }
-#endif
+#endif  // defined(OS_ANDROID)
+#endif  // BUILDFLAG(ENABLE_NATIVE_NOTIFICATIONS)
   return new MessageCenterDisplayService(
       Profile::FromBrowserContext(context),
       g_browser_process->notification_ui_manager());