Refactoring: move ownership of RtcEventLog from Call to PeerConnection

This CL is a pure refactoring which should not result in any functinal
changes. It moves ownership of the RtcEventLog from webrtc::Call to the
webrtc::PeerConnection object.

This is done so that we can add RtcEventLog support for ICE events -
which will require the TransportController to have a pointer to the
RtcEventLog. PeerConnection is the closest common owner of both Call and
TransportController (through WebRtcSession).

BUG=webrtc:6393

Review-Url: https://codereview.webrtc.org/2353033005
Cr-Commit-Position: refs/heads/master@{#14578}
diff --git a/webrtc/api/peerconnectioninterface_unittest.cc b/webrtc/api/peerconnectioninterface_unittest.cc
index d91336c..a4a11e1 100644
--- a/webrtc/api/peerconnectioninterface_unittest.cc
+++ b/webrtc/api/peerconnectioninterface_unittest.cc
@@ -558,12 +558,13 @@
 class PeerConnectionFactoryForTest : public webrtc::PeerConnectionFactory {
  public:
   webrtc::MediaControllerInterface* CreateMediaController(
-      const cricket::MediaConfig& config) const override {
+      const cricket::MediaConfig& config,
+      webrtc::RtcEventLog* event_log) const override {
     create_media_controller_called_ = true;
     create_media_controller_config_ = config;
 
     webrtc::MediaControllerInterface* mc =
-        PeerConnectionFactory::CreateMediaController(config);
+        PeerConnectionFactory::CreateMediaController(config, event_log);
     EXPECT_TRUE(mc != nullptr);
     return mc;
   }