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

content/browser/indexed_db/indexed_db_cursor.h

Index: content/browser/indexed_db/indexed_db_cursor.h
diff --git a/content/browser/indexed_db/indexed_db_cursor.h b/content/browser/indexed_db/indexed_db_cursor.h
index 72852f6651babe842faa4c26666725afe74b65b2..591f9f890502ab3b5be1299ee4c761b54560bebb 100644
--- a/content/browser/indexed_db/indexed_db_cursor.h
+++ b/content/browser/indexed_db/indexed_db_cursor.h
@@ -12,6 +12,7 @@
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
+#include "base/memory/weak_ptr.h"
 #include "content/browser/indexed_db/indexed_db_backing_store.h"
 #include "content/browser/indexed_db/indexed_db_database.h"
 #include "content/browser/indexed_db/indexed_db_transaction.h"
@@ -20,13 +21,13 @@
 
 namespace content {
 
-class CONTENT_EXPORT IndexedDBCursor
-    : NON_EXPORTED_BASE(public base::RefCounted<IndexedDBCursor>) {
+class CONTENT_EXPORT IndexedDBCursor {
  public:
   IndexedDBCursor(std::unique_ptr<IndexedDBBackingStore::Cursor> cursor,
                   indexed_db::CursorType cursor_type,
                   blink::WebIDBTaskType task_type,
                   IndexedDBTransaction* transaction);
+  ~IndexedDBCursor();
 
   void Advance(uint32_t count, scoped_refptr<IndexedDBCallbacks> callbacks);
   void Continue(std::unique_ptr<IndexedDBKey> key,
@@ -42,6 +43,8 @@ class CONTENT_EXPORT IndexedDBCursor
     return (cursor_type_ == indexed_db::CURSOR_KEY_ONLY) ? NULL
                                                          : cursor_->value();
   }
+
+  void RemoveCursorFromTransaction();
   void Close();
 
   leveldb::Status CursorIterationOperation(
@@ -59,13 +62,11 @@ class CONTENT_EXPORT IndexedDBCursor
       IndexedDBTransaction* transaction);
 
  private:
-  friend class base::RefCounted<IndexedDBCursor>;
-
-  ~IndexedDBCursor();
-
   blink::WebIDBTaskType task_type_;
   indexed_db::CursorType cursor_type_;
-  const scoped_refptr<IndexedDBTransaction> transaction_;
+
+  // We rely on the transaction calling Close() to clear this.
+  IndexedDBTransaction* transaction_;
 
   // Must be destroyed before transaction_.

[cmumford, 2016/12/01 19:14:51]

Should Close() assert that cursor_ is null?

[dmurph, 2016/12/01 21:12:23]

No, as the IndexedDBTransaction calls it in CloseAllCursors(). So we need it to
reset the cursor in that case.

   std::unique_ptr<IndexedDBBackingStore::Cursor> cursor_;
@@ -74,6 +75,8 @@ class CONTENT_EXPORT IndexedDBCursor
 
   bool closed_;
 
+  base::WeakPtrFactory<IndexedDBCursor> ptr_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(IndexedDBCursor);
 };