Moving yahoo_sport into pathological pageset and adding sync scroll.

tools/perf/page_sets/data/pathological_mobile_sites.json

 {
     "description": "Describes the Web Page Replay archives for a user story set. Don't edit by hand! Use record_wpr for updating.", 
     "archives": {
         "pathological_mobile_sites_000.wpr": [
             "http://edition.cnn.com", 
             "http://www.latimes.com", 
             "http://recode.net", 
             "http://www.pbs.org/newshour/bb/much-really-cost-live-city-like-seattle/#the-rundown", 
             "http://www.zdnet.com", 
             "http://m.espn.go.com/nhl/rankings"
+        ], 
+        "key_mobile_sites_000.wpr": [

[Sami, 2015/03/02 18:42:22]

I think this may be a little too fragile and/or weird. The next person who tries
to update the recording for key_mobile_sites might break this page set instead.

If the data in key_mobile_sites_000.wpr is good, how about checking in a copy of
it under the name pathological_mobile_sites_001.wpr?

+            "http://sports.yahoo.com/"
         ]
     }
 }