Wrap large IndexedDB values into Blobs before writing to LevelDB.

third_party/WebKit/Source/modules/indexeddb/IDBTransaction.h

Index: third_party/WebKit/Source/modules/indexeddb/IDBTransaction.h
diff --git a/third_party/WebKit/Source/modules/indexeddb/IDBTransaction.h b/third_party/WebKit/Source/modules/indexeddb/IDBTransaction.h
index 0f5eaed372837c3acdeac43dc18a3ffc5811ac60..76b9c5583f3483b8f3f3e68870c6898aea7ef658 100644
--- a/third_party/WebKit/Source/modules/indexeddb/IDBTransaction.h
+++ b/third_party/WebKit/Source/modules/indexeddb/IDBTransaction.h
@@ -33,6 +33,7 @@
 #include "modules/EventTargetModules.h"
 #include "modules/ModulesExport.h"
 #include "modules/indexeddb/IDBMetadata.h"
+#include "modules/indexeddb/IDBRequestQueue.h"
 #include "modules/indexeddb/IndexedDB.h"
 #include "platform/bindings/ActiveScriptWrappable.h"
 #include "platform/heap/Handle.h"
@@ -105,6 +106,15 @@ class MODULES_EXPORT IDBTransaction final
   void RegisterRequest(IDBRequest*);
   void UnregisterRequest(IDBRequest*);
 
+  // True if this transaction has at least one request whose result is being
+  // post-processed.
+  //
+  // While this is true, new results must be queued using QueueResult().
+  inline bool HasQueuedResult() const { return !result_queue_.empty(); }
+  void EnqueueResult(IDBRequestQueueItem* result);
+  // Called when a result's post-processing has completed.
+  void OnResultReady();
+
   // The methods below are called right before the changes are applied to the
   // database's metadata. We use this unusual sequencing because some of the
   // methods below need to access the metadata values before the change, and
@@ -212,6 +222,14 @@ class MODULES_EXPORT IDBTransaction final
 
   HeapListHashSet<Member<IDBRequest>> request_list_;
 
+  // The IDBRequest results whose events have not fired yet.
+  //
+  // When a result requires post-processing, such as large value unwrapping, all
+  // the results that arrive during the post-processing phase are queued up.
+  // This guarantees that result events are fired in the order in which the
+  // requests were performed, as prescribed by the IndexedDB specification.
+  IDBRequestQueue result_queue_;
+
 #if DCHECK_IS_ON()
   bool finish_called_ = false;
 #endif  // DCHECK_IS_ON()