Fix FakeNetworkPipe to not deliver packet faster than requested.

webrtc/video/end_to_end_tests.cc

Index: webrtc/video/end_to_end_tests.cc
diff --git a/webrtc/video/end_to_end_tests.cc b/webrtc/video/end_to_end_tests.cc
index 36d1cd184a9b495c891945d7e915ae0e62fd0b7e..8d1135a4ab93ef7b426b84b461e67861d74a5ff6 100644
--- a/webrtc/video/end_to_end_tests.cc
+++ b/webrtc/video/end_to_end_tests.cc
@@ -3285,13 +3285,7 @@ TEST_F(EndToEndTest, RespectsNetworkState) {
   RunBaseTest(&test);
 }
 
-// See: https://bugs.chromium.org/p/webrtc/issues/detail?id=5938
-#ifdef WEBRTC_MAC
-#define MAYBE_CallReportsRttForSender DISABLED_CallReportsRttForSender
-#else
-#define MAYBE_CallReportsRttForSender CallReportsRttForSender
-#endif
-TEST_F(EndToEndTest, MAYBE_CallReportsRttForSender) {
+TEST_F(EndToEndTest, CallReportsRttForSender) {
   static const int kSendDelayMs = 30;
   static const int kReceiveDelayMs = 70;