Add initial support for native Linux desktop notifications

chrome/common/chrome_features.cc

Index: chrome/common/chrome_features.cc
diff --git a/chrome/common/chrome_features.cc b/chrome/common/chrome_features.cc
index 278ad00e79c7796b3efe7eea35108c31406107c1..427a85d0e1aa13df9a34b00083f9709030d3cdd0 100644
--- a/chrome/common/chrome_features.cc
+++ b/chrome/common/chrome_features.cc
@@ -204,10 +204,10 @@ const base::Feature kModuleDatabase{"ModuleDatabase",
 
 // Enables the use of native notification centers instead of using the Message
 // Center for displaying the toasts.
-#if defined(OS_MACOSX)
+#if defined(OS_MACOSX) || (defined(OS_LINUX) && !defined(OS_CHROMEOS))
 const base::Feature kNativeNotifications{"NativeNotifications",
                                          base::FEATURE_DISABLED_BY_DEFAULT};
-#endif  // defined(OS_MACOSX)
+#endif  // defined(OS_MACOSX) || (defined(OS_LINUX) && !defined(OS_CHROMEOS))
 
 // If enabled, the list of content suggestions on the New Tab page will contain
 // pages that the user downloaded for later use.