Use SingleThreadTaskRunner instead of MessageLoopProxy in remoting/host.

remoting/host/chromoting_host_context_unittest.cc

Index: remoting/host/chromoting_host_context_unittest.cc
diff --git a/remoting/host/chromoting_host_context_unittest.cc b/remoting/host/chromoting_host_context_unittest.cc
index b48d3222baef063dca09ed6aa7271740a16666f9..3efa86844c7e5c0259070192e40d784a1cf7b14d 100644
--- a/remoting/host/chromoting_host_context_unittest.cc
+++ b/remoting/host/chromoting_host_context_unittest.cc
@@ -17,8 +17,8 @@ TEST(ChromotingHostContextTest, StartAndStop) {
 
   context.Start();
   EXPECT_TRUE(context.jingle_thread());
-  EXPECT_TRUE(context.main_message_loop());
-  EXPECT_TRUE(context.encode_message_loop());
+  EXPECT_TRUE(context.main_task_runner());
+  EXPECT_TRUE(context.encode_task_runner());
 }
 
 }  // namespace remoting