Add DCHECK to ensure IndexedDBDispatcher doesn't get re-created.

content/common/indexed_db/indexed_db_dispatcher.cc

 // Copyright (c) 2012 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 "content/common/indexed_db/indexed_db_dispatcher.h"
 
 #include "base/lazy_instance.h"
 #include "base/threading/thread_local.h"
 #include "content/common/child_thread.h"
 #include "content/common/indexed_db/indexed_db_messages.h"
@@ skipping 20 matching lines @@
 using WebKit::WebIDBDatabaseError;
 using WebKit::WebIDBTransaction;
 using WebKit::WebIDBTransactionCallbacks;
 using webkit_glue::WorkerTaskRunner;
 
 static base::LazyInstance<ThreadLocalPointer<IndexedDBDispatcher> >::Leaky
     g_idb_dispatcher_tls = LAZY_INSTANCE_INITIALIZER;
 
 namespace {
 
+IndexedDBDispatcher* const HAS_BEEN_DELETED =
+    reinterpret_cast<IndexedDBDispatcher*>(0x1);
+
 int32 CurrentWorkerId() {
   return WorkerTaskRunner::Instance()->CurrentWorkerId();
 }
 
 } // unnamed namespace
 
 const size_t kMaxIDBValueSizeInBytes = 64 * 1024 * 1024;
 
 IndexedDBDispatcher::IndexedDBDispatcher() {
   g_idb_dispatcher_tls.Pointer()->Set(this);
 }
 
 IndexedDBDispatcher::~IndexedDBDispatcher() {
-  g_idb_dispatcher_tls.Pointer()->Set(NULL);
+  g_idb_dispatcher_tls.Pointer()->Set(HAS_BEEN_DELETED);
 }
 
 IndexedDBDispatcher* IndexedDBDispatcher::ThreadSpecificInstance() {
+  if (g_idb_dispatcher_tls.Pointer()->Get() == HAS_BEEN_DELETED) {
+    NOTREACHED() << "Re-instantiating TLS IndexedDBDispatcher.";
+    g_idb_dispatcher_tls.Pointer()->Set(NULL);
+  }
   if (g_idb_dispatcher_tls.Pointer()->Get())
     return g_idb_dispatcher_tls.Pointer()->Get();
 
   IndexedDBDispatcher* dispatcher = new IndexedDBDispatcher;
   if (WorkerTaskRunner::Instance()->CurrentWorkerId())
     webkit_glue::WorkerTaskRunner::Instance()->AddStopObserver(dispatcher);
   return dispatcher;
 }
 
 void IndexedDBDispatcher::OnWorkerRunLoopStopped() {
@@ skipping 638 matching lines @@
 }
 
 void IndexedDBDispatcher::ResetCursorPrefetchCaches(int32 exception_cursor_id) {
   typedef std::map<int32, RendererWebIDBCursorImpl*>::iterator Iterator;
   for (Iterator i = cursors_.begin(); i != cursors_.end(); ++i) {
     if (i->first == exception_cursor_id)
       continue;
     i->second->ResetPrefetchCache();
   }
 }