Properly Remove Autofill Keyboard Listener.

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 ff96af2e105b448b97ee239b9b3c170011966807..015637a8b22373e86b5c8a78c43029d5b8d81dc4 100644
--- a/content/browser/renderer_host/render_widget_host_impl.cc
+++ b/content/browser/renderer_host/render_widget_host_impl.cc
@@ -1245,6 +1245,9 @@ void RenderWidgetHostImpl::AddKeyboardListener(KeyboardListener* listener) {
 
 void RenderWidgetHostImpl::RemoveKeyboardListener(
     KeyboardListener* listener) {
+  // Ensure that the element is actually in the list.
+  DCHECK(std::find(keyboard_listeners_.begin(), keyboard_listeners_.end(),
+                   listener) != keyboard_listeners_.end());
   keyboard_listeners_.remove(listener);
 }