Add enum value ScaleMethod::kFilterLinear.

webrtc/common_video/libyuv/include/scaler.h

Index: webrtc/common_video/libyuv/include/scaler.h
diff --git a/webrtc/common_video/libyuv/include/scaler.h b/webrtc/common_video/libyuv/include/scaler.h
index 2b92f8148b29cd397e0dca30d1a35bd28bc82518..6e3e05da0f9e7a061cbea3f3f496a398d3cf0950 100644
--- a/webrtc/common_video/libyuv/include/scaler.h
+++ b/webrtc/common_video/libyuv/include/scaler.h
@@ -23,8 +23,10 @@
 namespace webrtc {
 
 // Supported scaling types
+// Note: Must have the same values as libyuv::FilterMode.

[ossu, 2016/06/03 11:50:32]

So, the problem was it picked the wrong scaling mode due to a mismatch of enums?
Sounds like a dangerous practice. Why isn't ScaleMethod an alias for
libyuv::FilterMode if they need to be the same?

[nisse-webrtc, 2016/06/03 11:54:54]

That's my understanding, yes.
Good question. I would have done that, if it wasn't for my plan to delete this
code very soon (cl https://codereview.webrtc.org/2020593002/).

[ossu, 2016/06/03 12:37:15]

Ah! Then this one-liner really seems like the prudent choice.

 enum ScaleMethod {
   kScalePoint,  // no interpolation
+  kFilterLinear,
   kScaleBilinear,
   kScaleBox
 };