Use std::move in ResponseBodyLoader::Buffer::AddChunk

To move the newly-created chunk instead of copying it.

Bug: 1148064
Change-Id: Id1f0615f32ae58a010d7616fc347ee7b2ad228cd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2537508
Auto-Submit: Rakina Zata Amni <rakina@chromium.org>
Commit-Queue: Nate Chapin <japhet@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Nate Chapin <japhet@chromium.org>
Cr-Commit-Position: refs/heads/master@{#827828}

third_party/blink/renderer/platform/loader/fetch/response_body_loader.cc

@@ -288,7 +288,7 @@ class ResponseBodyLoader::Buffer final
   void AddChunk(const char* buffer, size_t available) {
     Vector<char> new_chunk;
     new_chunk.Append(buffer, available);
-    buffered_data_.emplace_back(new_chunk);
+    buffered_data_.emplace_back(std::move(new_chunk));
   }
 
   // Dispatches the frontmost chunk in |buffered_data_|. Returns the size of