Remove unused includes of platform/graphics/media/MediaPlayer.h

All of the these files either don't reference MediaPlayer anymore, or have
had uses replaced with uses of WebMediaPlayer instead.
Also update some comments that was referring to MediaPlayer, and remove
some other includes that was obviously not used.

BUG=350571

Review URL: https://codereview.chromium.org/851073003

git-svn-id: svn://svn.chromium.org/blink/trunk@188478 bbb929c8-8fbe-4397-9dbb-9b2b20218538
8 files changed
tree: 0b84cf7ad9f9cd563f2a8e1eab4e21af3adc3121
  1. third_party/