Add 'Flog' formatted logging to mojo/services

mojo/services/flog/cpp/flog.cc

+// Copyright 2016 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/services/flog/cpp/flog.h"
+
+namespace mojo {
+namespace flog {
+
+// static
+std::atomic_ulong Flog::last_allocated_channel_id_;
+
+// static
+FlogLoggerPtr Flog::logger_;
+
+FlogChannel::FlogChannel(const char* channel_type_name)
+    : id_(Flog::AllocateChannelId()) {
+  Flog::LogChannelCreation(id_, channel_type_name);
+}
+
+FlogChannel::~FlogChannel() {
+  Flog::LogChannelDeletion(id_);
+}
+
+bool FlogChannel::Accept(Message* message) {
+  Flog::LogChannelMessage(id_, message);
+  return true;
+}
+
+bool FlogChannel::AcceptWithResponder(Message* message,
+                                      MessageReceiver* responder) {
+  MOJO_DCHECK(false) << "Flog doesn't support messages with responses";
+  abort();
+}
+
+}  // namespace flog
+}  // namespace mojo