Check for delegate in OnMouseEvent

content/browser/renderer_host/render_widget_host_view_aura.cc

Index: content/browser/renderer_host/render_widget_host_view_aura.cc
diff --git a/content/browser/renderer_host/render_widget_host_view_aura.cc b/content/browser/renderer_host/render_widget_host_view_aura.cc
index fe86f4814f59e034d9e4cd5300c55dc1b185d744..ea3d544054ad4812ad8dc07b8ad51370e38a2395 100644
--- a/content/browser/renderer_host/render_widget_host_view_aura.cc
+++ b/content/browser/renderer_host/render_widget_host_view_aura.cc
@@ -522,7 +522,8 @@ bool RenderWidgetHostViewAura::OnMouseEvent(aura::MouseEvent* event) {
 
   // Needed to propagate mouse event to native_tab_contents_view_aura.
   // TODO(pkotwicz): Find a better way of doing this.
-  window_->parent()->delegate()->OnMouseEvent(event);
+  if (window_->parent()->delegate())
+    window_->parent()->delegate()->OnMouseEvent(event);
 
   // Return true so that we receive released/drag events.
   return true;