Remove calls to deprecated MessageLoop methods in mojo.

mojo/public/cpp/bindings/tests/multiplex_router_unittest.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "mojo/public/cpp/bindings/lib/multiplex_router.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/memory/ptr_util.h"
@@ skipping 26 matching lines @@
                                    base::ThreadTaskRunnerHandle::Get());
     router1_ = new MultiplexRouter(true, std::move(pipe.handle1),
                                    base::ThreadTaskRunnerHandle::Get());
     router0_->CreateEndpointHandlePair(&endpoint0_, &endpoint1_);
     endpoint1_ =
         EmulatePassingEndpointHandle(std::move(endpoint1_), router1_.get());
   }
 
   void TearDown() override {}
 
-  void PumpMessages() { loop_.RunUntilIdle(); }
+  void PumpMessages() { base::RunLoop().RunUntilIdle(); }
 
   ScopedInterfaceEndpointHandle EmulatePassingEndpointHandle(
       ScopedInterfaceEndpointHandle handle,
       MultiplexRouter* target) {
     CHECK(!handle.is_local());
 
     return target->CreateLocalEndpointHandle(handle.release());
   }
 
  protected:
@@ skipping 278 matching lines @@
 
   EXPECT_FALSE(generator.responder_is_valid());
   generator.CompleteWithResponse();  // This should end up doing nothing.
 }
 
 // TODO(yzshen): add more tests.
 
 }  // namespace
 }  // namespace test
 }  // namespace mojo