Late initialize MediaController, for less resource i.e. ProcessThread, usage by PeerConnection.

webrtc/api/peerconnectioninterface_unittest.cc

Index: webrtc/api/peerconnectioninterface_unittest.cc
diff --git a/webrtc/api/peerconnectioninterface_unittest.cc b/webrtc/api/peerconnectioninterface_unittest.cc
index 2c7cc128adeb03ea463895a84dc7499d98f99c48..429d676ae257a98319ac8354ad5393e5938c4b92 100644
--- a/webrtc/api/peerconnectioninterface_unittest.cc
+++ b/webrtc/api/peerconnectioninterface_unittest.cc
@@ -2364,6 +2364,10 @@ class PeerConnectionMediaConfigTest : public testing::Test {
     scoped_refptr<PeerConnectionInterface> pc(
         pcf_->CreatePeerConnection(config, constraints, nullptr, nullptr,
                                    &observer_));
+    {
+      rtc::scoped_refptr<RtpSenderInterface> sender(
+          pc->CreateSender(MediaStreamTrackInterface::kAudioKind, "foo_id"));

[tommi, 2016/02/22 15:22:05]

add a comment about why this is needed?  is the |sender| variable necessary?

[the sun, 2016/02/23 14:32:43]

Added comment. As for the variable, in theory we could just ignore the result,
but I think it tells the reader more to leave it in.

+    }
     EXPECT_TRUE(pc.get());
     EXPECT_TRUE(pcf_->create_media_controller_called_);
     return pcf_->create_media_controller_config_;