Stop using WebMediaPlayerClient::preload() and volume()

Stop using WebMediaPlayerClient::preload() and volume()

There is a "FIXME: Remove once calls on the Chromium-side have been
removed" for volume() in WebMediaPlayerClient.h. preload() is
similarly strange layering-wise, so get rid of that as well.

Simply store the values when they cannot immediately be forwarded to
the internal object.

In the case of WebMediaPlayerImpl::setVolume(), the value can always
be used immediately, so the setVolume() in DoLoad() appears to simply
have been unnecessary.

BUG=401415
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=288080

[philipj_slow, 2014-08-07 11:09:59]

PTAL. I don't venture into Chromium very often so look out for newbie mistakes.
I also don't really know how to test this, AFAICT there's no direct testing for
the WebMediaPlayer* implementations. I did some ad-hoc testing and it seems to
still work :/

[acolwell GONE FROM CHROMIUM, 2014-08-07 15:42:57]

lgtm

[philipj_slow, 2014-08-07 15:44:28]

The CQ bit was checked by philipj@opera.com

[commit-bot: I haz the power, 2014-08-07 15:45:33]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/philipj@opera.com/443393002/1

[commit-bot: I haz the power, 2014-08-07 16:42:35]

Change committed as 288080