MacViews: Clip contents for non-rectangular windows.

ui/views/BUILD.gn

Index: ui/views/BUILD.gn
diff --git a/ui/views/BUILD.gn b/ui/views/BUILD.gn
index 7c957c32cb697739d4afd7e6c571a2b2ecd226b1..0cd2da2a3a5a87cb41832f91b1d8075d0abf885b 100644
--- a/ui/views/BUILD.gn
+++ b/ui/views/BUILD.gn
@@ -132,6 +132,7 @@ component("views") {
 
   if (is_mac) {
     deps += [
+      "//third_party/google_toolbox_for_mac",
       "//ui/accelerated_widget_mac",
       "//ui/events:dom_keycode_converter",
     ]
@@ -290,7 +291,10 @@ test("views_unittests") {
       "controls/native/native_view_host_unittest.cc",
       "widget/window_reorderer_unittest.cc",
     ]
-    deps += [ "//ui/accelerated_widget_mac" ]
+    deps += [
+      "//third_party/google_toolbox_for_mac",
+      "//ui/accelerated_widget_mac",
+    ]
   }
 }