[Sync] Optimize move of EntityData

This CL implements actual move of parent_id field. This is important for
bookmarks data type during the initial merge when it is extensively
used.

This CL doesn't change the existing behaviour, it just optimizes
bookmarks initial merge.

Bug: 1168132
Change-Id: I65ebaba306057c608aa2401c112b1f1b22a4c6ed
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2640374Reviewed-by: Mikel Astiz <mastiz@chromium.org>
Commit-Queue: Rushan Suleymanov <rushans@google.com>
Cr-Commit-Position: refs/heads/master@{#846098}

components/sync/model/entity_data.cc

@@ -58,7 +58,7 @@ EntityData& EntityData::operator=(EntityData&& other) {
   name = std::move(other.name);
   creation_time = other.creation_time;
   modification_time = other.modification_time;
-  parent_id = other.parent_id;
+  parent_id = std::move(other.parent_id);
   is_folder = other.is_folder;
   is_bookmark_guid_in_specifics_preprocessed =
       other.is_bookmark_guid_in_specifics_preprocessed;