Remove the MessageLoop::DestructionObserver from mojo bindings.

mojo/public/cpp/bindings/lib/interface_endpoint_client.cc

Index: mojo/public/cpp/bindings/lib/interface_endpoint_client.cc
diff --git a/mojo/public/cpp/bindings/lib/interface_endpoint_client.cc b/mojo/public/cpp/bindings/lib/interface_endpoint_client.cc
index db34291a5363d7ecaff2bea57fad011873b2e146..a9eee86b6aa27ec93664b1937875287e68996ef2 100644
--- a/mojo/public/cpp/bindings/lib/interface_endpoint_client.cc
+++ b/mojo/public/cpp/bindings/lib/interface_endpoint_client.cc
@@ -159,15 +159,11 @@ InterfaceEndpointClient::InterfaceEndpointClient(
       handle_, this, task_runner_);
   if (expect_sync_requests)
     controller_->AllowWokenUpBySyncWatchOnSameThread();
-
-  base::MessageLoop::current()->AddDestructionObserver(this);
 }
 
 InterfaceEndpointClient::~InterfaceEndpointClient() {
   DCHECK(thread_checker_.CalledOnValidThread());
 
-  StopObservingIfNecessary();
-
   if (handle_.is_valid())
     handle_.group_controller()->DetachEndpointClient(handle_);
 }
@@ -351,17 +347,4 @@ bool InterfaceEndpointClient::HandleValidatedMessage(Message* message) {
   }
 }
 
-void InterfaceEndpointClient::StopObservingIfNecessary() {
-  if (!observing_message_loop_destruction_)
-    return;
-
-  observing_message_loop_destruction_ = false;
-  base::MessageLoop::current()->RemoveDestructionObserver(this);
-}
-
-void InterfaceEndpointClient::WillDestroyCurrentMessageLoop() {
-  StopObservingIfNecessary();
-  NotifyError(base::nullopt);
-}
-
 }  // namespace mojo