Make RTCStatsReport::ToString() return JSON-parseable string. BUG=chromium:653087 Review-Url: https://codereview.webrtc.org/2983243002 Cr-Commit-Position: refs/heads/master@{#19180}

diff --git a/webrtc/pc/rtcstats_integrationtest.cc b/webrtc/pc/rtcstats_integrationtest.cc
index 47fa0e3..56a4ef1 100644
--- a/webrtc/pc/rtcstats_integrationtest.cc
+++ b/webrtc/pc/rtcstats_integrationtest.cc

@@ -336,7 +336,7 @@
     }
     EXPECT_TRUE(verify_successful) <<
         "One or more problems with the stats. This is the report:\n" <<
-        report_->ToString();
+        report_->ToJson();
   }
 
   bool VerifyRTCCertificateStats(

diff --git a/webrtc/pc/rtcstatscollector_unittest.cc b/webrtc/pc/rtcstatscollector_unittest.cc
index 92024ad..8dc4a97 100644
--- a/webrtc/pc/rtcstatscollector_unittest.cc
+++ b/webrtc/pc/rtcstatscollector_unittest.cc

@@ -54,51 +54,51 @@
 
 // These are used by gtest code, such as if |EXPECT_EQ| fails.
 void PrintTo(const RTCCertificateStats& stats, ::std::ostream* os) {
-  *os << stats.ToString();
+  *os << stats.ToJson();
 }
 
 void PrintTo(const RTCCodecStats& stats, ::std::ostream* os) {
-  *os << stats.ToString();
+  *os << stats.ToJson();
 }
 
 void PrintTo(const RTCDataChannelStats& stats, ::std::ostream* os) {
-  *os << stats.ToString();
+  *os << stats.ToJson();
 }
 
 void PrintTo(const RTCIceCandidatePairStats& stats, ::std::ostream* os) {
-  *os << stats.ToString();
+  *os << stats.ToJson();
 }
 
 void PrintTo(const RTCLocalIceCandidateStats& stats, ::std::ostream* os) {
-  *os << stats.ToString();
+  *os << stats.ToJson();
 }
 
 void PrintTo(const RTCRemoteIceCandidateStats& stats, ::std::ostream* os) {
-  *os << stats.ToString();
+  *os << stats.ToJson();
 }
 
 void PrintTo(const RTCPeerConnectionStats& stats, ::std::ostream* os) {
-  *os << stats.ToString();
+  *os << stats.ToJson();
 }
 
 void PrintTo(const RTCMediaStreamStats& stats, ::std::ostream* os) {
-  *os << stats.ToString();
+  *os << stats.ToJson();
 }
 
 void PrintTo(const RTCMediaStreamTrackStats& stats, ::std::ostream* os) {
-  *os << stats.ToString();
+  *os << stats.ToJson();
 }
 
 void PrintTo(const RTCInboundRTPStreamStats& stats, ::std::ostream* os) {
-  *os << stats.ToString();
+  *os << stats.ToJson();
 }
 
 void PrintTo(const RTCOutboundRTPStreamStats& stats, ::std::ostream* os) {
-  *os << stats.ToString();
+  *os << stats.ToJson();
 }
 
 void PrintTo(const RTCTransportStats& stats, ::std::ostream* os) {
-  *os << stats.ToString();
+  *os << stats.ToJson();
 }
 
 namespace {