Close all active PeerConnections upon OS suspend (relanding r290125 and r291213)

content/renderer/media/rtc_peer_connection_handler.cc

Index: content/renderer/media/rtc_peer_connection_handler.cc
diff --git a/content/renderer/media/rtc_peer_connection_handler.cc b/content/renderer/media/rtc_peer_connection_handler.cc
index 7d2870a2bf6c084ded8f53c22c3e6cd7e0edd11c..c5c68e4d7418ba6b9d591e72cfbb5fd56e2e8657 100644
--- a/content/renderer/media/rtc_peer_connection_handler.cc
+++ b/content/renderer/media/rtc_peer_connection_handler.cc
@@ -782,6 +782,10 @@ void RTCPeerConnectionHandler::GetStats(
   }
 }
 
+void RTCPeerConnectionHandler::CloseClientPeerConnection() {
+  client_->closePeerConnection();
+}
+
 blink::WebRTCDataChannelHandler* RTCPeerConnectionHandler::createDataChannel(
     const blink::WebString& label, const blink::WebRTCDataChannelInit& init) {
   DVLOG(1) << "createDataChannel label " << base::UTF16ToUTF8(label);