Support generic synchronization against an IPC::Channel

ipc/ipc_message_pipe_reader.cc

Index: ipc/ipc_message_pipe_reader.cc
diff --git a/ipc/ipc_message_pipe_reader.cc b/ipc/ipc_message_pipe_reader.cc
index a20489bb41107cac098cdcdfc464c590c13c21b8..18a7ce0fde79dd8a62533b514b3d09f363670eed 100644
--- a/ipc/ipc_message_pipe_reader.cc
+++ b/ipc/ipc_message_pipe_reader.cc
@@ -84,6 +84,12 @@ void MessagePipeReader::GetRemoteInterface(
   sender_->GetAssociatedInterface(name, std::move(request));
 }
 
+void MessagePipeReader::SendEventToSignal(mojo::common::mojom::EventPtr event) {
+  if (!sender_.is_bound())
+    return;
+  sender_->SignalEvent(std::move(event));
+}
+
 void MessagePipeReader::SetPeerPid(int32_t peer_pid) {
   peer_pid_ = peer_pid;
   delegate_->OnPeerPidReceived();
@@ -121,6 +127,10 @@ void MessagePipeReader::GetAssociatedInterface(
     delegate_->OnAssociatedInterfaceRequest(name, request.PassHandle());
 }
 
+void MessagePipeReader::SignalEvent(mojo::common::mojom::EventPtr event) {
+  event->Signal();
+}
+
 void MessagePipeReader::OnPipeError(MojoResult error) {
   DCHECK(thread_checker_.CalledOnValidThread());