[MediaStream] Clean up RealtimeMediaSource settings change handling

[MediaStream] Clean up RealtimeMediaSource settings change handling
https://bugs.webkit.org/show_bug.cgi?id=189998
<rdar://problem/44797884>

Reviewed by Youenn Fablet.

No new tests, no change in functionality.

* platform/mediastream/RealtimeMediaSource.cpp:
(WebCore::RealtimeMediaSource::notifySettingsDidChangeObservers):
(WebCore::RealtimeMediaSource::setSize):
(WebCore::RealtimeMediaSource::setFrameRate):
(WebCore::RealtimeMediaSource::setAspectRatio):
(WebCore::RealtimeMediaSource::setFacingMode):
(WebCore::RealtimeMediaSource::setVolume):
(WebCore::RealtimeMediaSource::setSampleRate):
(WebCore::RealtimeMediaSource::setSampleSize):
(WebCore::RealtimeMediaSource::setEchoCancellation):
(WebCore::RealtimeMediaSource::settingsDidChange): Deleted.
* platform/mediastream/RealtimeMediaSource.h:
* platform/mediastream/mac/AVVideoCaptureSource.mm:
(WebCore::AVVideoCaptureSource::settingsDidChange):
* platform/mediastream/mac/CoreAudioCaptureSource.cpp:
(WebCore::CoreAudioCaptureSource::settingsDidChange):
* platform/mediastream/mac/DisplayCaptureSourceCocoa.cpp:
(WebCore::DisplayCaptureSourceCocoa::settingsDidChange):
* platform/mock/MockRealtimeAudioSource.cpp:
(WebCore::MockRealtimeAudioSource::settingsDidChange):
* platform/mock/MockRealtimeVideoSource.cpp:
(WebCore::MockRealtimeVideoSource::settingsDidChange):

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@236511 268f45cc-cd09-0410-ab3c-d52691b4dbfc