Adding GetConfiguration to PeerConnection.

Just returns the configuration the PC was constructed with, or the last
one passed into SetConfiguration.

BUG=chromium:587453

Review-Url: https://codereview.webrtc.org/2504103002
Cr-Commit-Position: refs/heads/master@{#15111}
diff --git a/webrtc/api/peerconnectioninterface.h b/webrtc/api/peerconnectioninterface.h
index ea056bf..a597c98 100644
--- a/webrtc/api/peerconnectioninterface.h
+++ b/webrtc/api/peerconnectioninterface.h
@@ -480,6 +480,11 @@
     return false;
   }
   virtual bool UpdateIce(const IceServers& configuration) { return false; }
+  // TODO(deadbeef): Make this pure virtual once all Chrome subclasses of
+  // PeerConnectionInterface implement it.
+  virtual PeerConnectionInterface::RTCConfiguration GetConfiguration() {
+    return PeerConnectionInterface::RTCConfiguration();
+  }
   // Sets the PeerConnection's global configuration to |config|.
   // Any changes to STUN/TURN servers or ICE candidate policy will affect the
   // next gathering phase, and cause the next call to createOffer to generate