Add unittests for CursorRendererMac

content/test/BUILD.gn

Index: content/test/BUILD.gn
diff --git a/content/test/BUILD.gn b/content/test/BUILD.gn
index abffb5506ffb985ec433fbae54bf174a47e2af07..0e7abb2a182282eda717713fe9728582ba50063e 100644
--- a/content/test/BUILD.gn
+++ b/content/test/BUILD.gn
@@ -1637,6 +1637,9 @@ test("content_unittests") {
     if (use_aura) {
       sources += [ "../browser/media/capture/cursor_renderer_aura_unittest.cc" ]
     }
+    if (is_mac) {
+      sources += [ "../browser/media/capture/cursor_renderer_mac_unittest.mm" ]
+    }
     if (is_chromeos) {
       sources +=
           [ "../browser/media/capture/desktop_capture_device_aura_unittest.cc" ]