Remove linked_ptr from HidReportDescriptor

This type is deprecated and easily replaced by std::unique_ptr.

Bug: 556939
Change-Id: I874bfdd9caf6366e0a9a119367d5e00ad9c2152f
Reviewed-on: https://chromium-review.googlesource.com/711214
Reviewed-by: Jun Cai <juncai@chromium.org>
Commit-Queue: Reilly Grant <reillyg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#507863}
2 files changed