Change WebRTC SslCipher to be exposed as number only.

talk/app/webrtc/peerconnectioninterface.h

Index: talk/app/webrtc/peerconnectioninterface.h
diff --git a/talk/app/webrtc/peerconnectioninterface.h b/talk/app/webrtc/peerconnectioninterface.h
index ca853385e6327fdcad52014b32abc115685e80c1..bccabef7cd9d761884d55729ae9d4240d9439c86 100644
--- a/talk/app/webrtc/peerconnectioninterface.h
+++ b/talk/app/webrtc/peerconnectioninterface.h
@@ -135,11 +135,17 @@ class MetricsObserverInterface : public rtc::RefCountInterface {
                                     int counter,
                                     int counter_max) {}
 
+  // Modeled against UMA_HISTOGRAM_SPARSE_SLOWLY which doesn't require a
+  // boundary value as UMA_HISTOGRAM_ENUMERATION. This is used to report sparse
+  // value like SSL cipher suite. TODO(guoweis): Remove the implmenetation once
+  // the code gets into chromium.
+  virtual void IncrementSparseEnumCounter(PeerConnectionEnumCounterType type,
+                                          int counter) {
+    IncrementEnumCounter(type, counter, 0 /* Ignored */);
+  }
+
   virtual void AddHistogramSample(PeerConnectionMetricsName type,
                                   int value) = 0;
-  // TODO(jbauch): Make method abstract when it is implemented by Chromium.
-  virtual void AddHistogramSample(PeerConnectionMetricsName type,
-                                  const std::string& value) {}
 
  protected:
   virtual ~MetricsObserverInterface() {}