ipc: Remove use of MessageLoopProxy and deprecated MessageLoop APIs

This patch was autogenerated with https://codereview.chromium.org/1010073002/.

BUG=465354

Review URL: https://codereview.chromium.org/1127153003

Cr-Commit-Position: refs/heads/master@{#329389}
diff --git a/ipc/ipc_perftest_support.cc b/ipc/ipc_perftest_support.cc
index 7144103..ae8be7f 100644
--- a/ipc/ipc_perftest_support.cc
+++ b/ipc/ipc_perftest_support.cc
@@ -342,7 +342,7 @@
 }
 
 scoped_refptr<base::TaskRunner> PingPongTestClient::task_runner() {
-  return main_message_loop_.message_loop_proxy();
+  return main_message_loop_.task_runner();
 }
 
 LockThreadAffinity::LockThreadAffinity(int cpu_number)