Replace scoped_ptr with std::unique_ptr in //media/base.

Plus some other bonus ones in media and some IWYU fixes.

TBR=brettw, dalecurtis
BUG=554298
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Review URL: https://codereview.chromium.org/1906423005

Cr-Commit-Position: refs/heads/master@{#389652}
139 files changed