Move WebMediaPlayer and friends to public/platform/

This is a prerequisite for eliminating the
MediaPlayer/MediaPlayerClient layer.

Minor style changes were needed to pass presubmit.

BUG=310466

Review URL: https://codereview.chromium.org/67083003

git-svn-id: svn://svn.chromium.org/blink/trunk@161792 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Make Blob constructor accept sequences.

The Blob constructor currently only accepts JS arrays for its first
argument (blob parts), but the WebIDL in the File spec says it should
accept any sequences (objects with the "length" property and indexed
properties). This change makes the Blob constructor compliant with the
spec.

BUG=314755

Review URL: https://codereview.chromium.org/67953004

git-svn-id: svn://svn.chromium.org/blink/trunk@161793 bbb929c8-8fbe-4397-9dbb-9b2b20218538