Fix crashing fake network pipe tests.

These tests are not included in bots, this will be fixed in a follow-up by pbos@webrtc.org.

R=pbos@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/13109004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@6837 4adac7df-926f-26a2-2b94-8c16560cd09d

webrtc/test/fake_network_pipe_unittest.cc

@@ -41,6 +41,8 @@ class FakeNetworkPipeTest : public ::testing::Test {
   virtual void SetUp() {
     TickTime::UseFakeClock(12345);
     receiver_.reset(new MockReceiver());
+    ON_CALL(*receiver_, DeliverPacket(_, _))
+        .WillByDefault(Return(PacketReceiver::DELIVERY_OK));
   }
 
   virtual void TearDown() {