Move SelectMediaType from RampUpTester to BaseTest.

webrtc/test/call_test.h

Index: webrtc/test/call_test.h
diff --git a/webrtc/test/call_test.h b/webrtc/test/call_test.h
index b4f665821ee2ffa420a6465835a4dc310e8b3961..b96e5e6e112a7e831c08f15ea8b5eb2b87d95259 100644
--- a/webrtc/test/call_test.h
+++ b/webrtc/test/call_test.h
@@ -192,7 +192,10 @@ class BaseTest : public RtpRtcpObserver {
   virtual Call::Config GetReceiverCallConfig();
   virtual void OnCallsCreated(Call* sender_call, Call* receiver_call);
 
-  // The default implementation creates MediaType::VIDEO transports.
+  // Returns VIDEO for video-only tests, AUDIO for audio-only tests,
+  // and ANY for tests sending audio and video over the same
+  // transport.
+  virtual MediaType SelectMediaType();
   virtual test::PacketTransport* CreateSendTransport(Call* sender_call);
   virtual test::PacketTransport* CreateReceiveTransport();