Vulkan: Remove std::unique_ptr usage from BufferVk::mBuffer BufferVk::mBuffer is std::unique_ptr mostly because BufferHelper object itself does not support move assignment. Now crrev.com/c/3366855 added move assignment support, we can now use BufferHelper directly. The main downside I can see is that in BufferVk::ghostMappedBuffer() and BufferVk::acquireAndUpdate() functions where we have to use move assignment of mBuffer object, it becomes slightly more expensive than moving pointer. But switch to using BufferHelper directly makes code simpler and other access to mBuffer (which is more common usage) slightly cheaper by removing one pointer indirection. Bug: b/208323792 Change-Id: Ia7e7731e284eb6c76db954fef194e9d1de82174b Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3362252 Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Tim Van Patten <timvp@google.com> Commit-Queue: Charlie Lao <cclao@google.com>