Revert of New method StatsObserver::OnCompleteReports, passing ownership.

webrtc/sdk/objc/Framework/Classes/RTCPeerConnection+Stats.mm

Index: webrtc/sdk/objc/Framework/Classes/RTCPeerConnection+Stats.mm
diff --git a/webrtc/sdk/objc/Framework/Classes/RTCPeerConnection+Stats.mm b/webrtc/sdk/objc/Framework/Classes/RTCPeerConnection+Stats.mm
index 4eb3e708f1a2543decdde0056086211a30893fa0..2c4571e0b37270198a3fc12fb3923d0cbb7640da 100644
--- a/webrtc/sdk/objc/Framework/Classes/RTCPeerConnection+Stats.mm
+++ b/webrtc/sdk/objc/Framework/Classes/RTCPeerConnection+Stats.mm
@@ -29,10 +29,10 @@
     completion_handler_ = nil;
   }
 
-  void OnCompleteReports(std::unique_ptr<StatsReports> reports) override {
+  void OnComplete(const StatsReports& reports) override {
     RTC_DCHECK(completion_handler_);
-    NSMutableArray *stats = [NSMutableArray arrayWithCapacity:reports->size()];
-    for (const auto* report : *reports) {
+    NSMutableArray *stats = [NSMutableArray arrayWithCapacity:reports.size()];
+    for (const auto* report : reports) {
       RTCLegacyStatsReport *statsReport =
           [[RTCLegacyStatsReport alloc] initWithNativeReport:*report];
       [stats addObject:statsReport];