Code:   LoadWatcher(ScriptContext* context,
              content::RenderFrame* frame,
              v8::Local<v8::Function> cb)
      : content::RenderFrameObserver(frame),
        context_(context),
        callback_(context->isolate(), cb) {
    if (ExtensionFrameHelper::Get(frame)->
            did_create_current_document_element()) {
      base::MessageLoop::current()->PostTask(
          FROM_HERE,
          base::Bind(&LoadWatcher::CallbackAndDie, base::Unretained(this),
                     true));
    }
   }

Vulnerability Type: DoS 
CWE ID: 
Summary: extensions/renderer/render_frame_observer_natives.cc in Google Chrome before 49.0.2623.75 does not properly consider object lifetimes and re-entrancy issues during OnDocumentElementCreated handling, which allows remote attackers to cause a denial of service (use-after-free) or possibly have unspecified other impact via unknown vectors.
Commit Message: Fix re-entrancy and lifetime issue in RenderFrameObserverNatives::OnDocumentElementCreated

BUG=585268,568130

Review URL: https://codereview.chromium.org/1684953002

Cr-Commit-Position: refs/heads/master@{#374758}