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

net/socket/transport_client_socket_pool_test_util.cc

Index: net/socket/transport_client_socket_pool_test_util.cc
diff --git a/net/socket/transport_client_socket_pool_test_util.cc b/net/socket/transport_client_socket_pool_test_util.cc
index 3dbffa61559e714dcc25085c5693c56bb3eea2e8..b524dcc766ab7062a9345ea781a3e07501250d8b 100644
--- a/net/socket/transport_client_socket_pool_test_util.cc
+++ b/net/socket/transport_client_socket_pool_test_util.cc
@@ -96,6 +96,7 @@ class MockConnectClientSocket : public StreamSocket {
   }
   int SetReceiveBufferSize(int32_t size) override { return OK; }
   int SetSendBufferSize(int32_t size) override { return OK; }
+  int SetDoNotFragment(bool do_not_fragment) override { return OK; }
 
  private:
   bool connected_;
@@ -161,6 +162,7 @@ class MockFailingClientSocket : public StreamSocket {
   }
   int SetReceiveBufferSize(int32_t size) override { return OK; }
   int SetSendBufferSize(int32_t size) override { return OK; }
+  int SetDoNotFragment(bool do_not_fragment) override { return OK; }
 
  private:
   const AddressList addrlist_;
@@ -288,6 +290,7 @@ class MockTriggerableClientSocket : public StreamSocket {
   }
   int SetReceiveBufferSize(int32_t size) override { return OK; }
   int SetSendBufferSize(int32_t size) override { return OK; }
+  int SetDoNotFragment(bool do_not_fragment) override { return OK; }
 
  private:
   void DoCallback() {