Reland: [IndexedDB] Delete callbacks state on worker thread exit.

content/child/indexed_db/indexed_db_dispatcher.h

 // 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.
 
 #ifndef CONTENT_CHILD_INDEXED_DB_INDEXED_DB_DISPATCHER_H_
 #define CONTENT_CHILD_INDEXED_DB_INDEXED_DB_DISPATCHER_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 67 matching lines @@
       IndexedDBCallbacksImpl::InternalState* callback_state);
   void RegisterMojoOwnedDatabaseCallbacks(
       blink::WebIDBDatabaseCallbacks* callback_state);
   void UnregisterMojoOwnedDatabaseCallbacks(
       blink::WebIDBDatabaseCallbacks* callback_state);
 
  private:
   FRIEND_TEST_ALL_PREFIXES(IndexedDBDispatcherTest, CursorReset);
   FRIEND_TEST_ALL_PREFIXES(IndexedDBDispatcherTest, CursorTransactionId);
 
+  // Looking up move-only entries in an std::unordered_set and removing them
+  // with out freeing them seems to be impossible so use a map instead so that
+  // the key type can remain a raw pointer.
+  using CallbackStateSet = std::unordered_map<
+      IndexedDBCallbacksImpl::InternalState*,
+      std::unique_ptr<IndexedDBCallbacksImpl::InternalState>>;
+  using DatabaseCallbackStateSet =
+      std::unordered_map<blink::WebIDBDatabaseCallbacks*,
+                         std::unique_ptr<blink::WebIDBDatabaseCallbacks>>;
+
   static int32_t CurrentWorkerId() { return WorkerThread::GetCurrentId(); }
 
   // IDBCallback message handlers.
   void OnDatabaseChanges(int32_t ipc_thread_id,
                          const IndexedDBMsg_ObserverChanges&);
 
   IDMap<blink::WebIDBObserver, IDMapOwnPointer> observers_;
   std::unordered_set<WebIDBCursorImpl*> cursors_;
 
   // Holds pointers to the worker-thread owned state of IndexedDBCallbacksImpl
   // and IndexedDBDatabaseCallbacksImpl objects to makes sure that it is
   // destroyed on thread exit if the Mojo pipe is not yet closed. Otherwise the
   // object will leak because the thread's task runner is no longer executing
   // tasks.
-  std::unordered_set<IndexedDBCallbacksImpl::InternalState*>
-      mojo_owned_callback_state_;
-  std::unordered_set<blink::WebIDBDatabaseCallbacks*>
-      mojo_owned_database_callback_state_;
+  CallbackStateSet mojo_owned_callback_state_;
+  DatabaseCallbackStateSet mojo_owned_database_callback_state_;
+  bool in_destructor_ = false;
 
   DISALLOW_COPY_AND_ASSIGN(IndexedDBDispatcher);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_CHILD_INDEXED_DB_INDEXED_DB_DISPATCHER_H_