extensions::ListBuilder move constructor doesn't transfer to a raw pointer.
extensions::ListBuilder move constructor doesn't transfer to a raw pointer.

This is mentioned on https://codereview.chromium.org/1497753002/.
extensions::ListBuilder's move constructor should not transfer ownership to a raw pointer(not to another scoped_ptr).

BUG=563649

Review URL: https://codereview.chromium.org/1510233005

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#364536}

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