[BlobReader] Correct IsInMemory = false when async constructing

storage/browser/blob/blob_reader.cc

 // Copyright 2015 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.
 
 #include "storage/browser/blob/blob_reader.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 208 matching lines @@
     read_callback_ = done;
   return status;
 }
 
 void BlobReader::Kill() {
   DeleteCurrentFileReader();
   weak_factory_.InvalidateWeakPtrs();
 }
 
 bool BlobReader::IsInMemory() const {
+  if (blob_handle_ && blob_handle_->IsBeingBuilt()) {
+    return false;
+  }
   if (!blob_data_.get()) {
     return true;
   }
   for (const auto& item : blob_data_->items()) {
     if (item->type() != DataElement::TYPE_BYTES) {
       return false;
     }
   }
   return true;
 }
@@ skipping 429 matching lines @@
       index_to_reader_.erase(found);
       return;
     }
     found->second = reader.release();
   } else if (reader.get()) {
     index_to_reader_[current_item_index_] = reader.release();
   }
 }
 
 }  // namespace storage