Mojo C++ bindings: make InterfaceEndpointClient observe message loop destruction.

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 6140cde5399374583bfef8d7cb53c0408e680d1c..df16ecfaeea4bfe11562d4e2f54be8a563ca8b90 100644
--- a/mojo/public/cpp/bindings/lib/interface_endpoint_client.cc
+++ b/mojo/public/cpp/bindings/lib/interface_endpoint_client.cc
@@ -159,11 +159,15 @@ 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_);
 }
@@ -336,4 +340,17 @@ 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();
+}
+
 }  // namespace mojo