Remove implicit conversions from scoped_refptr to T* in media/

This patch was generated by running the rewrite_scoped_refptr clang tool
on a Windows build.

BUG=110610
TBR=dalecurtis@chromium.org

Review URL: https://codereview.chromium.org/720983002

Cr-Commit-Position: refs/heads/master@{#304111}
10 files changed