content/child: Remove use of MessageLoopProxy and deprecated MessageLoop APIs

ppapi/proxy/ppapi_proxy_test.cc

Index: ppapi/proxy/ppapi_proxy_test.cc
diff --git a/ppapi/proxy/ppapi_proxy_test.cc b/ppapi/proxy/ppapi_proxy_test.cc
index fdd16043515d1bf506a78238cb84746146e22bb9..949dac39d2eee7c098f46d21a657a8c9d70c470d 100644
--- a/ppapi/proxy/ppapi_proxy_test.cc
+++ b/ppapi/proxy/ppapi_proxy_test.cc
@@ -235,8 +235,8 @@ void PluginProxyTestHarness::CreatePluginGlobals(
   }
 }
 
-base::MessageLoopProxy*
-PluginProxyTestHarness::PluginDelegateMock::GetIPCMessageLoop() {
+base::SingleThreadTaskRunner*
+PluginProxyTestHarness::PluginDelegateMock::GetIPCTaskRunner() {
   return ipc_message_loop_;
 }
 
@@ -470,8 +470,7 @@ void HostProxyTestHarness::CreateHostGlobals() {
   }
 }
 
-base::MessageLoopProxy*
-HostProxyTestHarness::DelegateMock::GetIPCMessageLoop() {
+base::MessageLoopProxy* HostProxyTestHarness::DelegateMock::GetIPCTaskRunner() {
   return ipc_message_loop_;
 }