Unbreak tabs.onRemove extension API in face of fast tab closure

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 dfc025b3bfed3b8b648df870464a2371b4a3174b..82238343cef21d1266d4cd494b41d91a2bfb0d99 100644
--- a/content/browser/web_contents/web_contents_impl.cc
+++ b/content/browser/web_contents/web_contents_impl.cc
@@ -350,6 +350,7 @@ WebContentsImpl::WebContentsImpl(
       notify_disconnection_(false),
       dialog_manager_(NULL),
       is_showing_before_unload_dialog_(false),
+      detached_as_part_of_unload_(false),
       closed_by_user_gesture_(false),
       minimum_zoom_percent_(static_cast<int>(kMinimumZoomFactor * 100)),
       maximum_zoom_percent_(static_cast<int>(kMaximumZoomFactor * 100)),
@@ -1978,6 +1979,10 @@ void WebContentsImpl::OnUnloadStarted() {
   before_unload_end_time_ = base::TimeTicks::Now();
 }
 
+void WebContentsImpl::OnUnloadAboutToDetach() {
+  detached_as_part_of_unload_ = true;
+}
+
 void WebContentsImpl::OnUnloadDetachedStarted() {
   if (unload_detached_start_time_.is_null())
     unload_detached_start_time_ = base::TimeTicks::Now();
@@ -2024,6 +2029,10 @@ bool WebContentsImpl::GetClosedByUserGesture() const {
   return closed_by_user_gesture_;
 }
 
+bool WebContentsImpl::GetWebContentsDetachedToClose() const {
+  return detached_as_part_of_unload_;
+}
+
 double WebContentsImpl::GetZoomLevel() const {
   HostZoomMapImpl* zoom_map = static_cast<HostZoomMapImpl*>(
       HostZoomMap::GetForBrowserContext(GetBrowserContext()));