diff --git a/api/BUILD.gn b/api/BUILD.gn
index 8e8b44ec51..cc4de43479 100644
--- a/api/BUILD.gn
+++ b/api/BUILD.gn
@@ -41,6 +41,7 @@ rtc_static_library("libjingle_peerconnection_api") {
     "cryptoparams.h",
     "datachannelinterface.h",
     "dtmfsenderinterface.h",
+    "jsep.cc",
     "jsep.h",
     "jsepicecandidate.h",
     "jsepsessiondescription.h",
diff --git a/api/jsep.cc b/api/jsep.cc
new file mode 100644
index 0000000000..1f4afbaca1
--- /dev/null
+++ b/api/jsep.cc
@@ -0,0 +1,24 @@
+/*
+ *  Copyright 2017 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "api/jsep.h"
+
+namespace webrtc {
+
+std::string IceCandidateInterface::server_url() const {
+  return "";
+}
+
+size_t SessionDescriptionInterface::RemoveCandidates(
+    const std::vector<cricket::Candidate>& candidates) {
+  return 0;
+}
+
+}  // namespace webrtc
diff --git a/api/jsep.h b/api/jsep.h
index c05f3829ae..581f689d1c 100644
--- a/api/jsep.h
+++ b/api/jsep.h
@@ -64,7 +64,7 @@ class IceCandidateInterface {
   // The URL of the ICE server which this candidate was gathered from.
   // TODO(zhihuang): Remove the default implementation once the subclasses
   // implement this method.
-  virtual std::string server_url() const { return ""; }
+  virtual std::string server_url() const;
   // Creates a SDP-ized form of this candidate.
   virtual bool ToString(std::string* out) const = 0;
 };
@@ -155,7 +155,7 @@ class SessionDescriptionInterface {
   //
   // Returns the number of candidates removed.
   virtual size_t RemoveCandidates(
-      const std::vector<cricket::Candidate>& candidates) { return 0; }
+      const std::vector<cricket::Candidate>& candidates);
 
   // Returns the number of m= sections in the session description.
   virtual size_t number_of_mediasections() const = 0;
@@ -200,7 +200,7 @@ class CreateSessionDescriptionObserver : public rtc::RefCountInterface {
   virtual void OnFailure(const std::string& error) = 0;
 
  protected:
-  ~CreateSessionDescriptionObserver() {}
+  ~CreateSessionDescriptionObserver() override = default;
 };
 
 // SetLocalDescription and SetRemoteDescription callback interface.
@@ -210,7 +210,7 @@ class SetSessionDescriptionObserver : public rtc::RefCountInterface {
   virtual void OnFailure(const std::string& error) = 0;
 
  protected:
-  ~SetSessionDescriptionObserver() {}
+  ~SetSessionDescriptionObserver() override = default;
 };
 
 }  // namespace webrtc