Don't wait to close tabs waiting for JavaScript dialogs.

content/browser/renderer_host/render_widget_host_impl.cc

Index: content/browser/renderer_host/render_widget_host_impl.cc
diff --git a/content/browser/renderer_host/render_widget_host_impl.cc b/content/browser/renderer_host/render_widget_host_impl.cc
index 666eb2928624addf63257443bac06471965721c4..17c42b5d38ee991b683b2ec9a1ad4d23be8c558b 100644
--- a/content/browser/renderer_host/render_widget_host_impl.cc
+++ b/content/browser/renderer_host/render_widget_host_impl.cc
@@ -907,12 +907,24 @@ void RenderWidgetHostImpl::StartHangMonitorTimeout(
     RenderWidgetHostDelegate::RendererUnresponsiveType hang_monitor_reason) {
   if (!hang_monitor_timeout_)
     return;
-  hang_monitor_timeout_->Start(delay);
+
   hang_monitor_reason_ = hang_monitor_reason;
+
+  // If the renderer is known to be unresponsive, don't bother waiting for it.
+  if (known_unresponsive_renderer_count_ > 0)
+    hang_monitor_timeout_->Start(base::TimeDelta());
+  else
+    hang_monitor_timeout_->Start(delay);
 }
 
 void RenderWidgetHostImpl::RestartHangMonitorTimeout() {
-  if (hang_monitor_timeout_)
+  if (!hang_monitor_timeout_)
+    return;
+
+  // If the renderer is known to be unresponsive, don't bother waiting for it.
+  if (known_unresponsive_renderer_count_ > 0)
+    hang_monitor_timeout_->Restart(base::TimeDelta());
+  else
     hang_monitor_timeout_->Restart(hung_renderer_delay_);
 }
 
@@ -930,6 +942,12 @@ void RenderWidgetHostImpl::StopHangMonitorTimeout() {
   RendererIsResponsive();
 }
 
+void RenderWidgetHostImpl::SetHangMonitorKnownUnresponsive(bool unresponsive) {
+  int count = unresponsive ? 1 : -1;
+  known_unresponsive_renderer_count_ += count;
+  DCHECK_GE(known_unresponsive_renderer_count_, 0);
+}
+
 void RenderWidgetHostImpl::StartNewContentRenderingTimeout() {
   // It is possible for a compositor frame to arrive before the browser is
   // notified about the page being committed, in which case no timer is