Basic framework for Budget API.

third_party/WebKit/Source/modules/budget/NavigatorBudget.cpp

+// 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 "modules/budget/NavigatorBudget.h"
+
+#include "core/frame/Navigator.h"
+#include "modules/budget/Budget.h"
+
+namespace blink {
+
+NavigatorBudget::NavigatorBudget()
+{
+}
+
+// static
+const char* NavigatorBudget::supplementName()
+{
+    return "NavigatorBudget";
+}
+
+// static
+NavigatorBudget& NavigatorBudget::from(Navigator& navigator)
+{
+    // Get the unique NavigatorBudget associated with this navigator.
+    NavigatorBudget* navigatorBudget = static_cast<NavigatorBudget*>(Supplement<Navigator>::from(navigator, supplementName()));
+    if (!navigatorBudget) {
+        // If there isn't one already, create it now and associate it.
+        navigatorBudget = new NavigatorBudget();
+        Supplement<Navigator>::provideTo(navigator, supplementName(), navigatorBudget);
+    }
+    return *navigatorBudget;
+}
+
+Budget* NavigatorBudget::budget()
+{
+    if (!m_budget)
+        m_budget = Budget::create();

[haraken, 2016/08/08 01:48:13]

Is there any benefit in instantiating m_budget lazily?

[harkness, 2016/08/08 12:07:36]

The Budget object is going to be a fairly heavy-weight object, and we don't
anticipate most webapps will use it at all, so avoiding creating one should be a
performance win.

+    return m_budget.get();
+}
+
+// static
+Budget* NavigatorBudget::budget(Navigator& navigator)
+{
+    return NavigatorBudget::from(navigator).budget();
+}
+
+DEFINE_TRACE(NavigatorBudget)
+{
+    visitor->trace(m_budget);
+    Supplement<Navigator>::trace(visitor);
+}
+
+} // namespace blink