Skip BeforeUnload on cross-site navigations when there are no handlers

content/browser/frame_host/render_frame_host_impl.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/frame_host/render_frame_host_impl.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/containers/hash_tables.h"
 #include "base/lazy_instance.h"
@@ skipping 902 matching lines @@
 
   // There may be no proxy if there are no active views in the process.
   int proxy_routing_id = MSG_ROUTING_NONE;
   FrameReplicationState replication_state;
   if (proxy) {
     set_render_frame_proxy_host(proxy);
     proxy_routing_id = proxy->GetRoutingID();
     replication_state = proxy->frame_tree_node()->current_replication_state();
   }
 
+  // TODO(clamy): if the frame has no unload handlers and |proxy| is null, it
+  // could be discarded immediately, improving performance. However that means
+  // losing the last sync of PageState.
   if (IsRenderFrameLive()) {
     Send(new FrameMsg_SwapOut(routing_id_, proxy_routing_id, is_loading,
                               replication_state));
   }
 
   if (!GetParent())
     delegate_->SwappedOut(this);
 }
 
 void RenderFrameHostImpl::OnBeforeUnloadACK(
@@ skipping 611 matching lines @@
       this, validated_url, source_site_instance, params.referrer,
       params.disposition, params.should_replace_current_entry,
       params.user_gesture);
 }
 
 void RenderFrameHostImpl::Stop() {
   Send(new FrameMsg_Stop(routing_id_));
 }
 
 void RenderFrameHostImpl::DispatchBeforeUnload(bool for_navigation) {
-  // TODO(creis): Support beforeunload on subframes.  For now just pretend that
+  // Skip running beforeUnload if:
+  //   - the renderer is not live.
+  //   - the frame is a subframe.
+  //   - this is a cross-site navigation and the current frame has no
+  //   beforeUnload handler registered.
+  // TODO(creis): Support beforeUnload on subframes.  For now just pretend that
   // the handler ran and allowed the navigation to proceed.
-  if (GetParent() || !IsRenderFrameLive()) {
-    // We don't have a live renderer, so just skip running beforeunload.
+  // TODO(clamy): Skip beforeUnload when closing a frame with no registered
+  // beforeUnload handlers.

[clamy, 2015/02/16 17:43:53]

We currently only skip waiting for beforeUnload in navigations because skipping
it on close require a lot of rewrite of the UnloadController and the
FastUnloadController in chrome which I did not want to do in that patch.

+  if (GetParent() || !IsRenderFrameLive() ||
+      (!has_beforeunload_handlers_ && for_navigation)) {
     if (base::CommandLine::ForCurrentProcess()->HasSwitch(
         switches::kEnableBrowserSideNavigation)) {
       frame_tree_node_->navigator()->OnBeforeUnloadACK(
           frame_tree_node_, true);
     } else {
       frame_tree_node_->render_manager()->OnBeforeUnloadACK(
           for_navigation, true, base::TimeTicks::Now());
     }
     return;
   }
@@ skipping 318 matching lines @@
 void RenderFrameHostImpl::DidUseGeolocationPermission() {
   RenderFrameHost* top_frame = frame_tree_node()->frame_tree()->GetMainFrame();
   GetContentClient()->browser()->RegisterPermissionUsage(
       PERMISSION_GEOLOCATION,
       delegate_->GetAsWebContents(),
       GetLastCommittedURL().GetOrigin(),
       top_frame->GetLastCommittedURL().GetOrigin());
 }
 
 }  // namespace content