PlzNavigate: properly execute BeforeUnload on renderer initiated navigations

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 8994b8d093f887cd8d38540fc01250776adc17f6..cb15dcad42600a890ed2a2f22da489d90424c264 100644
--- a/content/renderer/render_frame_impl.cc
+++ b/content/renderer/render_frame_impl.cc
@@ -1516,7 +1516,9 @@ void RenderFrameImpl::OnBeforeUnload() {
   CHECK(!frame_->parent());
 
   base::TimeTicks before_unload_start_time = base::TimeTicks::Now();
-  bool proceed = frame_->dispatchBeforeUnloadEvent();
+  bool proceed;
+  if (!frame_->dispatchBeforeUnloadEvent(&proceed))
+    return;
   base::TimeTicks before_unload_end_time = base::TimeTicks::Now();
   Send(new FrameHostMsg_BeforeUnload_ACK(routing_id_, proceed,
                                          before_unload_start_time,
@@ -4852,6 +4854,17 @@ WebNavigationPolicy RenderFrameImpl::decidePolicyForNavigation(
     return blink::WebNavigationPolicyIgnore;
   }
 
+  // Execute the BeforeUnload event. If asked not to proceed or the frame is
+  // destroyed, ignore the navigation.
+  bool proceed = false;
+  if (!IsBrowserSideNavigationEnabled() ||
+      info.urlRequest.checkForBrowserSideNavigation()) {
+    // PlzNavigate: this is not executed when commiting the navigation.
+    if (!frame_->dispatchBeforeUnloadEvent(&proceed) || !proceed) {
+      return blink::WebNavigationPolicyIgnore;
+    }
+  }
+
   // PlzNavigate: if the navigation is not synchronous, send it to the browser.
   // This includes navigations with no request being sent to the network stack.
   if (IsBrowserSideNavigationEnabled() &&
@@ -5603,7 +5616,6 @@ void RenderFrameImpl::BeginNavigation(blink::WebURLRequest* request,
                                       bool is_client_redirect) {
   CHECK(IsBrowserSideNavigationEnabled());
   DCHECK(request);
-  // TODO(clamy): Execute the beforeunload event.
 
   // Note: At this stage, the goal is to apply all the modifications the
   // renderer wants to make to the request, and then send it to the browser, so