[Storage] Consoliation of BlobItems with small size

storage/common/data_element.h

Index: storage/common/data_element.h
diff --git a/storage/common/data_element.h b/storage/common/data_element.h
index bdc881296acab626574d2981697c8a7f10cbeb2c..0efe1550a91e9a509d1cc0548854167a58c3a689 100644
--- a/storage/common/data_element.h
+++ b/storage/common/data_element.h
@@ -50,8 +50,28 @@ class STORAGE_COMMON_EXPORT DataElement {
     length_ = buf_.size();
   }
 
+  // Sets TYPE_BYTES data, and clears the internal bytes buffer.
+  // For use with AppendBytes.
+  void SetToEmptyBytes() {
+    type_ = TYPE_BYTES;
+    buf_.clear();
+    length_ = 0;
+    bytes_ = nullptr;
+  }
+
+  // Copies and appends the given data into the element. SetToEmptyBytes or
+  // SetToBytes must be called before this method.
+  void AppendBytes(const char* bytes, int bytes_len) {
+    DCHECK_EQ(type_, TYPE_BYTES);
+    DCHECK_NE(length_, kuint64max);
+    DCHECK(!bytes_);
+    buf_.insert(buf_.end(), bytes, bytes + bytes_len);
+    length_ = buf_.size();
+  }
+
   // Sets TYPE_BYTES data. This does NOT copy the given data and the caller
   // should make sure the data is alive when this element is accessed.
+  // You cannot use AppendBytes with this method.
   void SetToSharedBytes(const char* bytes, int bytes_len) {
     type_ = TYPE_BYTES;
     bytes_ = bytes;