Mojo: Armed Watchers

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

Index: mojo/public/cpp/bindings/lib/destruction_tracker.cc
diff --git a/mojo/public/cpp/bindings/lib/destruction_tracker.cc b/mojo/public/cpp/bindings/lib/destruction_tracker.cc
new file mode 100644
index 0000000000000000000000000000000000000000..9abfa11bc3c0d0fb296b67178e0fa3bba24e45b3
--- /dev/null
+++ b/mojo/public/cpp/bindings/lib/destruction_tracker.cc
@@ -0,0 +1,37 @@
+// Copyright 2017 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/public/cpp/bindings/lib/destruction_tracker.h"
+
+namespace mojo {
+
+DestructionTracker::Flag::Flag(DestructionTracker* tracker)
+    : tracker_(tracker), outer_flag_(tracker->flag_) {
+  tracker_->SetFlag(this);
+}
+
+DestructionTracker::Flag::~Flag() {
+  if (tracker_)
+    tracker_->SetFlag(outer_flag_);
+}
+
+void DestructionTracker::Flag::NotifyDestroyed() {
+  was_destroyed_ = true;
+  tracker_ = nullptr;
+  if (outer_flag_)
+    outer_flag_->NotifyDestroyed();
+}
+
+DestructionTracker::DestructionTracker() = default;
+
+DestructionTracker::~DestructionTracker() {
+  if (flag_)
+    flag_->NotifyDestroyed();
+}
+
+void DestructionTracker::SetFlag(Flag* flag) {
+  flag_ = flag;
+}
+
+}  // namespace mojo