Navigation transitions: Block first response until after transitions have run.

content/browser/web_contents/web_contents_impl.cc

Index: content/browser/web_contents/web_contents_impl.cc
diff --git a/content/browser/web_contents/web_contents_impl.cc b/content/browser/web_contents/web_contents_impl.cc
index f154585b299daa0eb03641e17ba460ee0c16b5bf..a105fb50160a8c33f08386624d68f77ad3dc0729 100644
--- a/content/browser/web_contents/web_contents_impl.cc
+++ b/content/browser/web_contents/web_contents_impl.cc
@@ -3477,6 +3477,11 @@ void WebContentsImpl::SwappedOut(RenderFrameHost* rfh) {
     delegate_->SwappedOut(this);
 }
 
+void WebContentsImpl::DidDeferAfterResponseStarted() {
+  FOR_EACH_OBSERVER(
+      WebContentsObserver, observers_, DidDeferAfterResponseStarted());
+}
+
 void WebContentsImpl::RequestMove(const gfx::Rect& new_bounds) {
   if (delegate_ && delegate_->IsPopupOrPanel(this))
     delegate_->MoveContents(this, new_bounds);
@@ -4081,4 +4086,9 @@ void WebContentsImpl::OnPreferredSizeChanged(const gfx::Size& old_size) {
     delegate_->UpdatePreferredSize(this, new_size);
 }
 
+void WebContentsImpl::ResumeResponseDeferredAtStart() {
+  FrameTreeNode* node = frame_tree_.root();
+  node->render_manager()->ResumeResponseDeferredAtStart();
+}
+
 }  // namespace content