[IndexedDB] Closing mojo connections when renderer quits

content/browser/indexed_db/cursor_impl.h

 // Copyright 2016 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_BROWSER_INDEXED_DB_CURSOR_IMPL_H_
 #define CONTENT_BROWSER_INDEXED_DB_CURSOR_IMPL_H_
 
 #include <memory>
 
 #include "base/memory/ref_counted.h"
 #include "content/common/indexed_db/indexed_db.mojom.h"
 
 namespace base {
-class SingleThreadTaskRunner;
+class SequencedTaskRunner;
 }
 
 namespace content {
 
 class IndexedDBCursor;
 class IndexedDBDispatcherHost;
 class IndexedDBKey;
 
+// Expected to be constructed, called, and destructed on the IO thread.
 class CursorImpl : public ::indexed_db::mojom::Cursor {
  public:
   CursorImpl(std::unique_ptr<IndexedDBCursor> cursor,
              const url::Origin& origin,
-             scoped_refptr<IndexedDBDispatcherHost> dispatcher_host);
+             IndexedDBDispatcherHost* dispatcher_host,
+             scoped_refptr<base::SequencedTaskRunner> idb_runner);
   ~CursorImpl() override;
 
   // ::indexed_db::mojom::Cursor implementation
   void Advance(
       uint32_t count,
       ::indexed_db::mojom::CallbacksAssociatedPtrInfo callbacks) override;
   void Continue(
       const IndexedDBKey& key,
       const IndexedDBKey& primary_key,
       ::indexed_db::mojom::CallbacksAssociatedPtrInfo callbacks) override;
   void Prefetch(
       int32_t count,
       ::indexed_db::mojom::CallbacksAssociatedPtrInfo callbacks) override;
   void PrefetchReset(
       int32_t used_prefetches,
       int32_t unused_prefetches,
       const std::vector<std::string>& unused_blob_uuids) override;
 
  private:
   class IDBThreadHelper;
 
   IDBThreadHelper* helper_;
-  scoped_refptr<IndexedDBDispatcherHost> dispatcher_host_;
+  // This raw pointer is safe because all CursorImpl instances are owned by an
+  // IndexedDBDispatcherHost.
+  IndexedDBDispatcherHost* dispatcher_host_;
   const url::Origin origin_;
-  scoped_refptr<base::SingleThreadTaskRunner> idb_runner_;
+  scoped_refptr<base::SequencedTaskRunner> idb_runner_;
 
   DISALLOW_COPY_AND_ASSIGN(CursorImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_INDEXED_DB_CURSOR_IMPL_H_