Remove internal methods from global namespace.

It's rude to clobber our consumers global namespace.

Bug: None
Change-Id: If8073820fcae6399def1717775fa64bc6e20051c
Reviewed-on: https://webrtc-review.googlesource.com/3165
Reviewed-by: Magnus Jedvert <magjed@webrtc.org>
Commit-Queue: Kári Helgason <kthelgason@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#19942}

sdk/objc/Framework/Classes/VideoToolbox/RTCVideoEncoderH264.mm

@@ -49,6 +49,8 @@
 
 @end
 
+namespace {  // anonymous namespace
+
 // The ratio between kVTCompressionPropertyKey_DataRateLimits and
 // kVTCompressionPropertyKey_AverageBitRate. The data rate limit is set higher
 // than the average bit rate to avoid undershooting the target.
@@ -268,6 +270,7 @@ CFStringRef ExtractProfile(const cricket::VideoCodec &codec) {
       }
   }
 }
+}  // namespace
 
 @implementation RTCVideoEncoderH264 {
   RTCVideoCodecInfo *_codecInfo;