Revert of Move the event attach/detach logic on unload from event.js to

extensions/renderer/dispatcher.cc

 // Copyright 2014 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/dispatcher.h"
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/command_line.h"
 #include "base/debug/alias.h"
@@ skipping 347 matching lines @@
 
 void Dispatcher::WillReleaseScriptContext(
     blink::WebLocalFrame* frame,
     const v8::Handle<v8::Context>& v8_context,
     int world_id) {
   ScriptContext* context = script_context_set_.GetByV8Context(v8_context);
   if (!context)
     return;
 
   context->DispatchOnUnloadEvent();
-  // TODO(kalman): Make |request_sender| use |context->AddInvalidationObserver|.
-  // In fact |request_sender_| should really be owned by ScriptContext.
+  // TODO(kalman): add an invalidation observer interface to ScriptContext.
   request_sender_->InvalidateSource(context);
 
   script_context_set_.Remove(context);
   VLOG(1) << "Num tracked contexts: " << script_context_set_.size();
 }
 
 void Dispatcher::DidCreateDocumentElement(blink::WebFrame* frame) {
   // Note: use GetEffectiveDocumentURL not just frame->document()->url()
   // so that this also injects the stylesheet on about:blank frames that
   // are hosted in the extension process.
@@ skipping 1181 matching lines @@
   // The "guestViewDeny" module must always be loaded last. It registers
   // error-providing custom elements for the GuestView types that are not
   // available, and thus all of those types must have been checked and loaded
   // (or not loaded) beforehand.
   if (context_type == Feature::BLESSED_EXTENSION_CONTEXT) {
     module_system->Require("guestViewDeny");
   }
 }
 
 }  // namespace extensions