[Sync] Replace uses of ObserverListThreadSafe with WeakHandles

chrome/browser/sync/js/js_mutation_event_observer.cc

 // Copyright (c) 2011 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 "chrome/browser/sync/js/js_mutation_event_observer.h"
 
 #include <string>
 
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/string_number_conversions.h"
 #include "base/values.h"
 #include "chrome/browser/sync/js/js_event_details.h"
 #include "chrome/browser/sync/js/js_event_handler.h"
 
 namespace browser_sync {
 
-JsMutationEventObserver::JsMutationEventObserver() {}
+JsMutationEventObserver::JsMutationEventObserver()
+    : weak_ptr_factory_(ALLOW_THIS_IN_INITIALIZER_LIST(this)) {}
 
 JsMutationEventObserver::~JsMutationEventObserver() {
   DCHECK(non_thread_safe_.CalledOnValidThread());
 }
 
+base::WeakPtr<JsMutationEventObserver> JsMutationEventObserver::AsWeakPtr() {
+  return weak_ptr_factory_.GetWeakPtr();
+}
+
+void JsMutationEventObserver::InvalidateWeakPtrs() {
+  weak_ptr_factory_.InvalidateWeakPtrs();
+}
+
 void JsMutationEventObserver::SetJsEventHandler(
     const WeakHandle<JsEventHandler>& event_handler) {
   event_handler_ = event_handler;
 }
 
 void JsMutationEventObserver::OnTransactionStart(
     const tracked_objects::Location& location,
     const syncable::WriterTag& writer) {
   DCHECK(non_thread_safe_.CalledOnValidThread());
   if (!event_handler_.IsInitialized()) {
@@ skipping 86 matching lines @@
     const std::string& name, const JsEventDetails& details) {
   if (!event_handler_.IsInitialized()) {
     NOTREACHED();
     return;
   }
   event_handler_.Call(from_here,
                       &JsEventHandler::HandleJsEvent, name, details);
 }
 
 }  // namespace browser_sync