Stop using nested message loop for alert() and other JS dialogs

content/renderer/render_frame_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/renderer/render_frame_impl.h"
 
 #include <map>
 #include <string>
 #include <utility>
 #include <vector>
@@ skipping 2111 matching lines @@
     return;
   }
 
   Send(new FrameHostMsg_TextSurroundingSelectionResponse(
       routing_id_,
       surroundingText.textContent(),
       surroundingText.startOffsetInTextContent(),
       surroundingText.endOffsetInTextContent()));
 }
 
-bool RenderFrameImpl::SendAndRunNestedMessageLoop(IPC::SyncMessage* message) {
+bool RenderFrameImpl::SendSyncMessage(IPC::SyncMessage* message) {
   // Before Blink asks us to show an alert (etc.), it takes care of doing the
   // equivalent of WebView::willEnterModalLoop.  In this case it is particularly

[aelias_OOO_until_Jul13, 2016/04/29 05:50:38]

Could you track down what this "equivalent" is and delete it?

[Changwan Ryu, 2016/04/29 08:44:13]

Currently, FlashMessageLoop and PrintWebViewHelper will still call
willEnterModalLoop() to pause resource dispatching until their sync messages get
replied. I'm not sure about the impact of removing the logic in those cases.

   // important that we do not call willEnterModalLoop as that would defer
   // resource loads for the dialog itself.
   if (RenderThreadImpl::current())  // Will be NULL during unit tests.
     RenderThreadImpl::current()->DoNotNotifyWebKitOfModalLoop();

[aelias_OOO_until_Jul13, 2016/04/29 05:50:38]

This is now unneeded, and there is some more code you can delete as part of this
patch if you follow down this thread.  Please delete both
RenderFrameImpl::SendSyncMessage and RenderThreadImpl::Send() entirely (without
the nested message loop, it looks correct to simply call ChildThreadImpl::Send)
as well as RenderThreadImpl::notify_webkit_of_modal_loop_.

[Changwan Ryu, 2016/04/29 08:44:13]

Removed notify_webkit_of_modal_loop and related function.
RenderFrameImpl::Send() has a logic to check for a detaching message,
so I left it as is.

 
-  message->EnableMessagePumping();  // Runs a nested message loop.
   return Send(message);
 }
 
 bool RenderFrameImpl::RunJavaScriptMessage(JavaScriptMessageType type,
                                            const base::string16& message,
                                            const base::string16& default_value,
                                            const GURL& frame_url,
                                            base::string16* result) {
   // Don't allow further dialogs if we are waiting to swap out, since the
   // ScopedPageLoadDeferrer in our stack prevents it.
   if (suppress_further_dialogs_)
     return false;
 
   bool success = false;
   base::string16 result_temp;
   if (!result)
     result = &result_temp;
 
-  SendAndRunNestedMessageLoop(new FrameHostMsg_RunJavaScriptMessage(
+  SendSyncMessage(new FrameHostMsg_RunJavaScriptMessage(
       routing_id_, message, default_value, frame_url, type, &success, result));
   return success;
 }
 
 void RenderFrameImpl::LoadNavigationErrorPage(
     const WebURLRequest& failed_request,
     const WebURLError& error,
     bool replace) {
   std::string error_html;
   GetContentClient()->renderer()->GetNavigationErrorStrings(
@@ skipping 1458 matching lines @@
 bool RenderFrameImpl::runModalBeforeUnloadDialog(bool is_reload) {
   // Don't allow further dialogs if we are waiting to swap out, since the
   // ScopedPageLoadDeferrer in our stack prevents it.
   if (suppress_further_dialogs_)
     return false;
 
   bool success = false;
   // This is an ignored return value, but is included so we can accept the same
   // response as RunJavaScriptMessage.
   base::string16 ignored_result;
-  SendAndRunNestedMessageLoop(new FrameHostMsg_RunBeforeUnloadConfirm(
+  SendSyncMessage(new FrameHostMsg_RunBeforeUnloadConfirm(
       routing_id_, frame_->document().url(), is_reload, &success,
       &ignored_result));
   return success;
 }
 
 void RenderFrameImpl::showContextMenu(const blink::WebContextMenuData& data) {
   ContextMenuParams params = ContextMenuParamsBuilder::Build(data);
   blink::WebRect position_in_window(params.x, params.y, 0, 0);
   GetRenderWidget()->convertViewportToWindow(&position_in_window);
   params.x = position_in_window.x;
@@ skipping 2387 matching lines @@
                                     int match_count,
                                     int ordinal,
                                     const WebRect& selection_rect,
                                     bool final_status_update) {
   Send(new FrameHostMsg_Find_Reply(routing_id_, request_id, match_count,
                                    selection_rect, ordinal,
                                    final_status_update));
 }
 
 }  // namespace content