Make IndexedDBConnection IDs independent from the IPC database ID.

content/browser/indexed_db/indexed_db_connection.h

Index: content/browser/indexed_db/indexed_db_connection.h
diff --git a/content/browser/indexed_db/indexed_db_connection.h b/content/browser/indexed_db/indexed_db_connection.h
index d8b72dfc1c28575e2866c378c2b4eb64c1027fc5..7c4f5160a9b32d063bc2cee27110438da4309464 100644
--- a/content/browser/indexed_db/indexed_db_connection.h
+++ b/content/browser/indexed_db/indexed_db_connection.h
@@ -38,7 +38,6 @@ class CONTENT_EXPORT IndexedDBConnection {
   // connection.
   virtual void RemoveObservers(const std::vector<int32_t>& remove_observer_ids);
 
-  void set_id(int32_t id);
   int32_t id() const { return id_; }
 
   IndexedDBDatabase* database() const { return database_.get(); }
@@ -52,9 +51,7 @@ class CONTENT_EXPORT IndexedDBConnection {
   }
 
  private:
-  enum { kInvalidId = -1 };
-  // id_ is ipc_database_id
-  int32_t id_ = kInvalidId;
+  const int32_t id_;
 
   // NULL in some unit tests, and after the connection is closed.
   scoped_refptr<IndexedDBDatabase> database_;