Keep track in the browser of which frames have onunload and onbeforeunload handlers.

content/renderer/render_frame_impl.cc

Index: content/renderer/render_frame_impl.cc
diff --git a/content/renderer/render_frame_impl.cc b/content/renderer/render_frame_impl.cc
index 679773f82aca83ced3397903a82c2e4dd7c899e6..421ae065cfbcd6d2d3f951423709ef3852372ac9 100644
--- a/content/renderer/render_frame_impl.cc
+++ b/content/renderer/render_frame_impl.cc
@@ -4756,6 +4756,21 @@ void RenderFrameImpl::exitFullscreen() {
   Send(new FrameHostMsg_ToggleFullscreen(routing_id_, false));
 }
 
+void RenderFrameImpl::suddenTerminationDisablerChanged(
+    bool present,
+    blink::WebFrameClient::SuddenTerminationDisablerType type) {
+  switch (type) {
+    case blink::WebFrameClient::BeforeUnloadHandler:
+      Send(new FrameHostMsg_BeforeUnloadHandlersPresent(routing_id_, present));
+      break;
+    case blink::WebFrameClient::UnloadHandler:
+      Send(new FrameHostMsg_UnloadHandlersPresent(routing_id_, present));
+      break;
+    default:

[nasko, 2017/03/29 23:31:26]

Omitting the default: clause should be fine and will allow the compiler to
enforce that all possible enum values are checked in the switch statement.

+      NOTREACHED();
+  }
+}
+
 void RenderFrameImpl::registerProtocolHandler(const WebString& scheme,
                                               const WebURL& url,
                                               const WebString& title) {