Histogram the scheme of an origin on the 1st navigation to it.

chrome/browser/tab_contents/origins_seen_service_factory.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 CHROME_BROWSER_TAB_CONTENTS_ORIGINS_SEEN_SERVICE_FACTORY_H_
+#define CHROME_BROWSER_TAB_CONTENTS_ORIGINS_SEEN_SERVICE_FACTORY_H_
+
+#include "base/memory/singleton.h"
+#include "chrome/browser/tab_contents/origins_seen_service.h"
+#include "components/keyed_service/content/browser_context_keyed_service_factory.h"
+
+class OriginsSeenService;
+
+class OriginsSeenServiceFactory : public BrowserContextKeyedServiceFactory {
+ public:
+  static OriginsSeenService* GetForBrowserContext(
+      content::BrowserContext* context);
+
+  static OriginsSeenServiceFactory* GetInstance();
+
+  // Used to create instances for testing.
+  static KeyedService* BuildInstanceFor(content::BrowserContext* context);
+
+ private:
+  friend struct base::DefaultSingletonTraits<OriginsSeenServiceFactory>;
+
+  OriginsSeenServiceFactory();
+  ~OriginsSeenServiceFactory() override;
+
+  // BrowserContextKeyedServiceFactory:
+  content::BrowserContext* GetBrowserContextToUse(
+      content::BrowserContext* context) const override;
+  KeyedService* BuildServiceInstanceFor(
+      content::BrowserContext* context) const override;
+};
+
+#endif  // CHROME_BROWSER_TAB_CONTENTS_ORIGINS_SEEN_SERVICE_FACTORY_H_