Revert "Remove MediaStreamTrack.getSources()."

third_party/WebKit/Source/core/frame/Deprecation.cpp

Index: third_party/WebKit/Source/core/frame/Deprecation.cpp
diff --git a/third_party/WebKit/Source/core/frame/Deprecation.cpp b/third_party/WebKit/Source/core/frame/Deprecation.cpp
index 7cf0c1230c27251bdff3121e0f51482f8751e929..0e1022e9d7dc831c0b3d5a4338f80ea001387b33 100644
--- a/third_party/WebKit/Source/core/frame/Deprecation.cpp
+++ b/third_party/WebKit/Source/core/frame/Deprecation.cpp
@@ -402,6 +402,10 @@ String Deprecation::deprecationMessage(UseCounter::Feature feature) {
       return replacedBy("'Performance.onwebkitresourcetimingbufferfull'",
                         "'Performance.onresourcetimingbufferfull'");
 
+    case UseCounter::MediaStreamTrackGetSources:
+      return willBeRemoved("MediaStreamTrack.getSources", M56,
+                           "4765305641369600");
+
     case UseCounter::WebAnimationHyphenatedProperty:
       return "Hyphenated property names in Web Animations keyframes are "
              "invalid and therefore ignored. Please use camelCase instead.";