[Telemetry] Change story disabling in webrtc pageset to StoryExpectations.

tools/perf/page_sets/webrtc_cases.py

Index: tools/perf/page_sets/webrtc_cases.py
diff --git a/tools/perf/page_sets/webrtc_cases.py b/tools/perf/page_sets/webrtc_cases.py
index 62bc5b2004b70c67f279d72e57fa562cd510cdf0..50e5e57391ce6c6f37547a6470a76526395b3333 100644
--- a/tools/perf/page_sets/webrtc_cases.py
+++ b/tools/perf/page_sets/webrtc_cases.py
@@ -125,8 +125,7 @@ class WebrtcPageSet(story.StorySet):
         cloud_storage_bucket=story.PUBLIC_BUCKET)
 
     self.AddStory(GetUserMedia(self, tags=['getusermedia']))
-    # TODO(ehmaldonado): Re-enable once http://crbug.com/725502 is fixed.
-    # self.AddStory(MultiplePeerConnections(self, tags=['stress']))
+    self.AddStory(MultiplePeerConnections(self, tags=['stress']))
     self.AddStory(VideoCall(self, tags=['peerconnection', 'smoothness']))
     self.AddStory(DataChannel(self, tags=['datachannel']))
     self.AddStory(CanvasCapturePeerConnection(self, tags=['smoothness']))
@@ -137,3 +136,9 @@ class WebrtcPageSet(story.StorySet):
     # self.AddStory(AudioCall(self, 'G772'))
     # self.AddStory(AudioCall(self, 'PCMU'))
     # self.AddStory(AudioCall(self, 'ISAC/1600'))
+
+
+class WebrtcExpectations(story.expectations.StoryExpectations):
+  def SetExpectations(self):
+    self.DisableStory('multiple_peerconnections', [story.expectations.ALL],
+                      'crbug.com/725502')