Introduce struct MediaConfig, with construction-time settings.

webrtc/media/base/videoengine_unittest.h

Index: webrtc/media/base/videoengine_unittest.h
diff --git a/webrtc/media/base/videoengine_unittest.h b/webrtc/media/base/videoengine_unittest.h
index 1b2aedf6b76f80796fdc416bb7898c2c9c075f68..f9aa3f3579a9b726195f020447c1236ce8bd335e 100644
--- a/webrtc/media/base/videoengine_unittest.h
+++ b/webrtc/media/base/videoengine_unittest.h
@@ -143,7 +143,9 @@ class VideoMediaChannelTest : public testing::Test,
     cricket::Device device("test", "device");
     engine_.Init();
     channel_.reset(
-        engine_.CreateChannel(call_.get(), cricket::VideoOptions()));
+                   engine_.CreateChannel(call_.get(),
+                                         cricket::MediaConfig(),
+                                         cricket::VideoOptions()));
     EXPECT_TRUE(channel_.get() != NULL);
     network_interface_.SetDestination(channel_.get());
     channel_->SetInterface(&network_interface_);