[IndexedDB] Refactoring to remove ref ptrs and host transaction ids.

content/browser/indexed_db/cursor_impl.cc

Index: content/browser/indexed_db/cursor_impl.cc
diff --git a/content/browser/indexed_db/cursor_impl.cc b/content/browser/indexed_db/cursor_impl.cc
index 6e4d2198180248a3431960ce935652a6cb1d79a1..e711d8dd76724422d9afe18bd2a45ac2215dc15d 100644
--- a/content/browser/indexed_db/cursor_impl.cc
+++ b/content/browser/indexed_db/cursor_impl.cc
@@ -12,7 +12,7 @@ namespace content {
 
 class CursorImpl::IDBThreadHelper {
  public:
-  explicit IDBThreadHelper(scoped_refptr<IndexedDBCursor> cursor);
+  explicit IDBThreadHelper(std::unique_ptr<IndexedDBCursor> cursor);
   ~IDBThreadHelper();
 
   void Advance(uint32_t count, scoped_refptr<IndexedDBCallbacks> callbacks);
@@ -24,13 +24,13 @@ class CursorImpl::IDBThreadHelper {
 
  private:
   scoped_refptr<IndexedDBDispatcherHost> dispatcher_host_;
-  scoped_refptr<IndexedDBCursor> cursor_;
+  std::unique_ptr<IndexedDBCursor> cursor_;
   const url::Origin origin_;
 
   DISALLOW_COPY_AND_ASSIGN(IDBThreadHelper);
 };
 
-CursorImpl::CursorImpl(scoped_refptr<IndexedDBCursor> cursor,
+CursorImpl::CursorImpl(std::unique_ptr<IndexedDBCursor> cursor,
                        const url::Origin& origin,
                        scoped_refptr<IndexedDBDispatcherHost> dispatcher_host)
     : helper_(new IDBThreadHelper(std::move(cursor))),
@@ -88,10 +88,12 @@ void CursorImpl::PrefetchReset(
 }
 
 CursorImpl::IDBThreadHelper::IDBThreadHelper(
-    scoped_refptr<IndexedDBCursor> cursor)
+    std::unique_ptr<IndexedDBCursor> cursor)
     : cursor_(std::move(cursor)) {}
 
-CursorImpl::IDBThreadHelper::~IDBThreadHelper() {}
+CursorImpl::IDBThreadHelper::~IDBThreadHelper() {
+  cursor_->RemoveCursorFromTransaction();
+}
 
 void CursorImpl::IDBThreadHelper::Advance(
     uint32_t count,