Make RTCStatsReport::ToString() return JSON-parseable string.

webrtc/api/stats/rtcstats.h

Index: webrtc/api/stats/rtcstats.h
diff --git a/webrtc/api/stats/rtcstats.h b/webrtc/api/stats/rtcstats.h
index 6730672012abd919b088d0a7bbf6341d4c50796c..d9ed7bc2f6df2601f531c28d9c7cc937ba4f5c0a 100644
--- a/webrtc/api/stats/rtcstats.h
+++ b/webrtc/api/stats/rtcstats.h
@@ -72,9 +72,9 @@ class RTCStats {
   bool operator==(const RTCStats& other) const;
   bool operator!=(const RTCStats& other) const;
 
-  // Creates a human readable string representation of the stats object, listing
-  // all of its members (names and values).
-  std::string ToString() const;
+  // Creates a JSON readable string representation of the stats
+  // object, listing all of its members (names and values).
+  std::string ToJson() const;
 
   // Downcasts the stats object to an |RTCStats| subclass |T|. DCHECKs that the
   // object is of type |T|.
@@ -222,6 +222,12 @@ class RTCStatsMemberInterface {
     return !(*this == other);
   }
   virtual std::string ValueToString() const = 0;
+  // This is the same as ValueToString except for kInt64 and kUint64 types,
+  // where the value is represented as a double instead of as an integer.
+  // Since JSON stores numbers as floating point numbers, very large integers
+  // cannot be accurately represented, so we prefer to display them as doubles
+  // instead.
+  virtual std::string ValueToJson() const = 0;
 
   template<typename T>
   const T& cast_to() const {
@@ -277,6 +283,7 @@ class RTCStatsMember : public RTCStatsMemberInterface {
     return value_ == other_t.value_;
   }
   std::string ValueToString() const override;
+  std::string ValueToJson() const override;
 
   // Assignment operators.
   T& operator=(const T& value) {