Deal with frame removal by content scripts

extensions/renderer/extension_frame_helper.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "extensions/renderer/extension_frame_helper.h"
 
 #include "base/strings/string_util.h"
 #include "content/public/renderer/render_frame.h"
 #include "extensions/common/api/messaging/message.h"
 #include "extensions/common/constants.h"
@@ skipping 105 matching lines @@
 void ExtensionFrameHelper::DidCreateDocumentElement() {
   did_create_current_document_element_ = true;
   extension_dispatcher_->DidCreateDocumentElement(
       render_frame()->GetWebFrame());
 }
 
 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) {
   extension_dispatcher_->content_watcher()->DidMatchCSS(
       render_frame()->GetWebFrame(), newly_matching_selectors,
       stopped_matching_selectors);
 }
 
 void ExtensionFrameHelper::DidCreateScriptContext(
     v8::Local<v8::Context> context,
@@ skipping 92 matching lines @@
     const std::string& module_name,
     const std::string& function_name,
     const base::ListValue& args,
     bool user_gesture) {
   extension_dispatcher_->InvokeModuleSystemMethod(render_frame(), extension_id,
                                                   module_name, function_name,
                                                   args, user_gesture);
 }
 
 }  // namespace extensions