Adding DRP specfic UMA for FirstContentfulPaint

content/public/browser/navigation_data.h

+// 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.
+
+#ifndef CONTENT_PUBLIC_BROWSER_NAVIGATION_DATA_H_
+#define CONTENT_PUBLIC_BROWSER_NAVIGATION_DATA_H_
+
+#include <memory>
+
+namespace content {
+
+// Copyable interface for embedders to pass opaque data to content/. It is
+// expected to be created on the IO thread, and content/ will transfer it to the
+// UI thread as a clone.
+class NavigationData {
+ public:
+  virtual ~NavigationData(){};
+
+  // Creates a new NavigationData that is a deep copy of the original
+  virtual std::unique_ptr<NavigationData> Clone() const = 0;
+};
+
+}  // namespace content
+
+#endif  // CONTENT_PUBLIC_BROWSER_NAVIGATION_DATA_H_