Linux native notifications: Support closing and updating notifications

ui/base/glib/scoped_gobject.h

+// Copyright 2017 The Chromium Authors. All rights reserved.

[Peter Beverloo, 2017/04/06 17:56:57]

Should probably add this to //ui/base/BUILD.gn?

(Even though it's not a compilation unit, there was a thread on chromium-dev@
about missing files about a week ago.)

[Tom (Use chromium acct), 2017/04/06 18:25:38]

Done.

+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef UI_BASE_GLIB_GLIB_UTIL_H_
+#define UI_BASE_GLIB_GLIB_UTIL_H_
+
+#include "base/logging.h"
+
+// Similar in spirit to a std::unique_ptr.
+template <typename T>
+class ScopedGObject {
+ public:
+  ScopedGObject() : obj_(nullptr) {}
+
+  explicit ScopedGObject(T* obj) : obj_(obj) {
+    // Remove the floating reference from |obj_| if it has one.
+    if (g_object_is_floating(obj_))
+      g_object_ref_sink(obj_);
+    DCHECK(G_OBJECT(obj_)->ref_count == 1);
+  }
+
+  ScopedGObject(const ScopedGObject<T>& other) = delete;
+
+  ScopedGObject(ScopedGObject<T>&& other) : obj_(other.obj_) {
+    other.obj_ = nullptr;
+  }
+
+  ~ScopedGObject() { reset(nullptr); }
+
+  ScopedGObject<T>& operator=(const ScopedGObject<T>& other) = delete;
+
+  ScopedGObject<T>& operator=(ScopedGObject<T>&& other) {
+    g_object_unref(obj_);
+    obj_ = other.obj_;
+    other.obj_ = nullptr;
+    return *this;
+  }
+
+  operator T*() { return obj_; }
+
+  void reset(T* obj) {
+    if (obj_)
+      Unref();
+    obj_ = obj;
+  }
+
+ private:
+  void Unref() { g_object_unref(obj_); }
+
+  T* obj_;
+};
+
+#endif  // UI_BASE_GLIB_GLIB_UTIL_H_