Add a SetDoNotFragment() method to DatagramSocket, and call this for

net/socket/socket_test_util.h

Index: net/socket/socket_test_util.h
diff --git a/net/socket/socket_test_util.h b/net/socket/socket_test_util.h
index de8ba34376b9f217925e6599fecd7a7cad0084be..6923c4eb21d6cfcb168a96578f5a4f08ec9f83d1 100644
--- a/net/socket/socket_test_util.h
+++ b/net/socket/socket_test_util.h
@@ -560,6 +560,7 @@ class MockClientSocket : public SSLClientSocket {
             const CompletionCallback& callback) override = 0;
   int SetReceiveBufferSize(int32_t size) override;
   int SetSendBufferSize(int32_t size) override;
+  int SetDoNotFragment(bool do_not_fragment) override;
 
   // StreamSocket implementation.
   int Connect(const CompletionCallback& callback) override = 0;
@@ -740,6 +741,7 @@ class MockUDPClientSocket : public DatagramClientSocket, public AsyncSocket {
             const CompletionCallback& callback) override;
   int SetReceiveBufferSize(int32_t size) override;
   int SetSendBufferSize(int32_t size) override;
+  int SetDoNotFragment(bool do_not_fragment) override;
 
   // DatagramSocket implementation.
   void Close() override;