Quickly close tabs/window with long-running unload handlers.

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 c09ad4df91122d240b7d91f9a9d0893a74823af9..26b3d73350fda90c47d5317497139284c4ec1254 100644
--- a/content/browser/web_contents/web_contents_impl.cc
+++ b/content/browser/web_contents/web_contents_impl.cc
@@ -403,11 +403,17 @@ WebContentsImpl::~WebContentsImpl() {
   // OnCloseStarted isn't called in unit tests.
   if (!close_start_time_.is_null()) {
     base::TimeTicks now = base::TimeTicks::Now();
+    base::TimeDelta close_time = now - close_start_time_;
+    UMA_HISTOGRAM_TIMES("Tab.Close", close_time);
+
     base::TimeTicks unload_start_time = close_start_time_;
+    base::TimeTicks unload_end_time = now;
     if (!before_unload_end_time_.is_null())
       unload_start_time = before_unload_end_time_;
-    UMA_HISTOGRAM_TIMES("Tab.Close", now - close_start_time_);
-    UMA_HISTOGRAM_TIMES("Tab.Close.UnloadTime", now - unload_start_time);
+    if (!unload_detached_start_time_.is_null())
+      unload_end_time = unload_detached_start_time_;
+    base::TimeDelta unload_time = unload_end_time - unload_start_time;
+    UMA_HISTOGRAM_TIMES("Tab.Close.UnloadTime", unload_time);
   }
 
   FOR_EACH_OBSERVER(WebContentsObserver,
@@ -1796,8 +1802,15 @@ void WebContentsImpl::Close() {
 }
 
 void WebContentsImpl::OnCloseStarted() {
-  if (close_start_time_.is_null())
+  if (close_start_time_.is_null()) {
     close_start_time_ = base::TimeTicks::Now();
+  }
+}
+
+void WebContentsImpl::OnUnloadDetachedStarted() {
+  if (unload_detached_start_time_.is_null()) {
+    unload_detached_start_time_ = base::TimeTicks::Now();
+  }
 }
 
 bool WebContentsImpl::ShouldAcceptDragAndDrop() const {
@@ -3364,6 +3377,7 @@ void WebContentsImpl::OnDialogClosed(RenderViewHost* rvh,
 
     close_start_time_ = base::TimeTicks();
     before_unload_end_time_ = base::TimeTicks();
+    unload_detached_start_time_ = base::TimeTicks();
   }
   is_showing_before_unload_dialog_ = false;
   static_cast<RenderViewHostImpl*>(