Mojo C++ bindings: support closing [Associated]InterfaceRequest with reason.

mojo/public/cpp/bindings/associated_interface_request.h

Index: mojo/public/cpp/bindings/associated_interface_request.h
diff --git a/mojo/public/cpp/bindings/associated_interface_request.h b/mojo/public/cpp/bindings/associated_interface_request.h
index 30fcd16ec14496d30ae318aa240ed46cedb0b75a..361b301d38957d8eed565d4364d87e2e94920f01 100644
--- a/mojo/public/cpp/bindings/associated_interface_request.h
+++ b/mojo/public/cpp/bindings/associated_interface_request.h
@@ -5,9 +5,15 @@
 #ifndef MOJO_PUBLIC_CPP_BINDINGS_ASSOCIATED_INTERFACE_REQUEST_H_
 #define MOJO_PUBLIC_CPP_BINDINGS_ASSOCIATED_INTERFACE_REQUEST_H_
 
+#include <string>
 #include <utility>
 
 #include "base/macros.h"
+#include "base/memory/ptr_util.h"
+#include "base/threading/thread_task_runner_handle.h"
+#include "mojo/public/cpp/bindings/interface_endpoint_client.h"
+#include "mojo/public/cpp/bindings/lib/control_message_proxy.h"
+#include "mojo/public/cpp/bindings/message.h"
 #include "mojo/public/cpp/bindings/scoped_interface_endpoint_handle.h"
 
 namespace mojo {
@@ -64,6 +70,28 @@ class AssociatedInterfaceRequest {
     return !is_pending() && !other.is_pending();
   }
 
+  void ResetWithReason(uint32_t custom_reason, const std::string& description) {
+    if (!handle_.is_valid())
+      return;
+
+    if (!handle_.is_local()) {
+      // This handle is supposed to be sent to the other end of the message
+      // pipe and used there.
+      NOTREACHED();
+      handle_.reset();
+      return;
+    }
+
+    InterfaceEndpointClient client(std::move(handle_), nullptr,
+                                   base::MakeUnique<PassThroughFilter>(), false,
+                                   base::ThreadTaskRunnerHandle::Get(), 0u);
+    Message message =
+        internal::ControlMessageProxy::ConstructDisconnectReasonMessage(
+            custom_reason, description);
+    bool result = client.Accept(&message);
+    DCHECK(result);
+  }
+
  private:
   ScopedInterfaceEndpointHandle handle_;