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

chrome/browser/tab_contents/origins_seen_service_factory.cc

+// 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 "chrome/browser/tab_contents/origins_seen_service_factory.h"
+
+#include "chrome/browser/profiles/incognito_helpers.h"
+#include "chrome/browser/profiles/profile.h"
+#include "components/keyed_service/content/browser_context_dependency_manager.h"
+
+// static
+OriginsSeenService* OriginsSeenServiceFactory::GetForProfile(Profile* profile) {
+  return static_cast<OriginsSeenService*>(
+      GetInstance()->GetServiceForBrowserContext(profile, true));
+}
+
+// static
+OriginsSeenServiceFactory* OriginsSeenServiceFactory::GetInstance() {
+  return base::Singleton<OriginsSeenServiceFactory>::get();
+}
+
+// static
+KeyedService* OriginsSeenServiceFactory::BuildInstanceFor(Profile* profile) {
+  return new OriginsSeenService();
+}
+
+OriginsSeenServiceFactory::OriginsSeenServiceFactory()
+    : BrowserContextKeyedServiceFactory(
+          "OriginsSeenService",
+          BrowserContextDependencyManager::GetInstance()) {}
+
+OriginsSeenServiceFactory::~OriginsSeenServiceFactory() {}
+
+KeyedService* OriginsSeenServiceFactory::BuildServiceInstanceFor(
+    content::BrowserContext* profile) const {
+  return BuildInstanceFor(static_cast<Profile*>(profile));
+}