Linux native notifications: Add initial unit test

chrome/test/BUILD.gn

Index: chrome/test/BUILD.gn
diff --git a/chrome/test/BUILD.gn b/chrome/test/BUILD.gn
index 6419c2c6a8b7c690aca517c32dc6be2cd13f41c6..ca019697d52141039e0cd741d4cef65badd2d1c7 100644
--- a/chrome/test/BUILD.gn
+++ b/chrome/test/BUILD.gn
@@ -3651,6 +3651,10 @@ test("unit_tests") {
     ]
   }
 
+  if (is_desktop_linux && enable_native_notifications) {

[Lei Zhang, 2017/04/29 01:35:05]

Curiuos why the mac version isn't gated on similar logic.

[Tom (Use chromium acct), 2017/05/01 18:25:29]

The mac version doesn't need to be conditioned on enable_native_notifications
because it doesn't have the additional use_dbus dependency the Linux version
has.

Also, ninja only includes files with _mac in the filename in the mac version, so
it doesn't even need is_mac.

+    sources += [ "../browser/notifications/notification_platform_bridge_linux_unittest.cc" ]
+  }
+
   if (is_linux || is_win) {
     sources += [ "../browser/webshare/share_service_impl_unittest.cc" ]
   }