sync: Remove SyncSourceInfo

sync/sessions/nudge_tracker.h

Index: sync/sessions/nudge_tracker.h
diff --git a/sync/sessions/nudge_tracker.h b/sync/sessions/nudge_tracker.h
index f8109a42d38e7460920a4d1a7017cf75f989ae15..8d8839e33fcf937845a67a601ad3d59a0796b928 100644
--- a/sync/sessions/nudge_tracker.h
+++ b/sync/sessions/nudge_tracker.h
@@ -20,8 +20,6 @@
 namespace syncer {
 namespace sessions {
 
-struct SyncSourceInfo;
-
 class SYNC_EXPORT_PRIVATE NudgeTracker {
  public:
   static size_t kDefaultMaxPayloadsPerType;
@@ -78,10 +76,6 @@ class SYNC_EXPORT_PRIVATE NudgeTracker {
   // Returns the set of currently throttled types.
   ModelTypeSet GetThrottledTypes() const;
 
-  // A helper to return an old-style source info.  Used only to maintain
-  // compatibility with some old code.
-  SyncSourceInfo GetSourceInfo() const;
-
   // Returns the 'source' of the GetUpdate request.
   //
   // This flag is deprecated, but still used by the server.  There can be more