Re-enable Vp9FlexModeRefCount

webrtc/video/video_send_stream_tests.cc

Index: webrtc/video/video_send_stream_tests.cc
diff --git a/webrtc/video/video_send_stream_tests.cc b/webrtc/video/video_send_stream_tests.cc
index 6c4b06ce3a3539f3e0bc9e63fc466b2755ff7285..7991095983338cdd1f9523c120a010373ea0282b 100644
--- a/webrtc/video/video_send_stream_tests.cc
+++ b/webrtc/video/video_send_stream_tests.cc
@@ -2280,9 +2280,6 @@ TEST_F(VideoSendStreamTest, Vp9NonFlexModeSmallResolution) {
   RunBaseTest(&test);
 }
 
-#if !defined(MEMORY_SANITIZER)
-// Fails under MemorySanitizer:
-// See https://code.google.com/p/webrtc/issues/detail?id=5402.
 TEST_F(VideoSendStreamTest, Vp9FlexModeRefCount) {
   class FlexibleMode : public Vp9HeaderObserver {
     void ModifyVideoConfigsHook(
@@ -2307,6 +2304,5 @@ TEST_F(VideoSendStreamTest, Vp9FlexModeRefCount) {
 
   RunBaseTest(&test);
 }
-#endif
 
 }  // namespace webrtc