Deal with frame removal by content scripts

extensions/renderer/extension_frame_helper.cc

Index: extensions/renderer/extension_frame_helper.cc
diff --git a/extensions/renderer/extension_frame_helper.cc b/extensions/renderer/extension_frame_helper.cc
index c063f84a169ba2a5d6915b6cdc121647f9b93e2c..ecc951e95b98970369edb5b985d9d839774daf5b 100644
--- a/extensions/renderer/extension_frame_helper.cc
+++ b/extensions/renderer/extension_frame_helper.cc
@@ -123,6 +123,27 @@ void ExtensionFrameHelper::DidCreateNewDocument() {
   did_create_current_document_element_ = false;
 }
 
+void ExtensionFrameHelper::AfterDidCreateDocumentElement(
+    const base::WeakPtr<content::RenderFrame>& render_frame_weak) {
+  DCHECK_EQ(render_frame(), render_frame_weak.get());
+  DCHECK(did_create_current_document_element_);
+
+  // The JavaScript code can cause re-entrancy. To avoid a deadlock, don't run
+  // callbacks that are added during the iteration.
+  std::vector<base::Closure> callbacks;
+  document_element_created_callbacks_.swap(callbacks);
+  for (auto& callback : callbacks) {
+    callback.Run();
+    if (!render_frame_weak.get())
+      return;  // Frame invalidated by callback.

[ncarter (slow), 2016/02/11 22:47:32]

That also means that |this| was deleted (right?).

I'm not super familiar with this code, but as an aesthetic measure, it might be
worth considering moving this loop out into calling code (i.e. expose something
like a "vector<Callback> GetAndClearDocumentElementCreatedCallbacks()").

[robwu, 2016/02/11 23:36:51]

Yes.
I prefer to keep it in this class, since then all (frame-specific!) callback
registration and running logic is within this class.

+  }
+}
+
+void ExtensionFrameHelper::ScheduleAfterDidCreateDocumentElement(
+    const base::Closure& callback) {
+  document_element_created_callbacks_.push_back(callback);
+}
+
 void ExtensionFrameHelper::DidMatchCSS(
     const blink::WebVector<blink::WebString>& newly_matching_selectors,
     const blink::WebVector<blink::WebString>& stopped_matching_selectors) {