GN: Remove non-existing header file: media/base/videorenderer.h

This header was removed in https://codereview.webrtc.org/1819103003
but the BUILD.gn file was not updated.

BUG=webrtc:5949
NOTRY=True
TBR=nisse@webrtc.org

Review-Url: https://codereview.webrtc.org/2359113002
Cr-Commit-Position: refs/heads/master@{#14349}

webrtc/media/BUILD.gn

@@ -88,7 +88,6 @@ rtc_source_set("rtc_media") {
     "base/videoframe.h",
     "base/videoframefactory.cc",
     "base/videoframefactory.h",
-    "base/videorenderer.h",
     "base/videosourcebase.cc",
     "base/videosourcebase.h",
     "devices/videorendererfactory.h",