Componentize OriginsSeenService & provide iOS factory.

ios/chrome/browser/metrics/ios_chrome_origins_seen_service_factory.h

Index: ios/chrome/browser/metrics/ios_chrome_origins_seen_service_factory.h
diff --git a/ios/chrome/browser/metrics/ios_chrome_origins_seen_service_factory.h b/ios/chrome/browser/metrics/ios_chrome_origins_seen_service_factory.h
new file mode 100644
index 0000000000000000000000000000000000000000..a4507d9807ad3b763b5684463b7bcac91514c16e
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+++ b/ios/chrome/browser/metrics/ios_chrome_origins_seen_service_factory.h
@@ -0,0 +1,51 @@
+// 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 IOS_CHROME_BROWSER_METRICS_IOS_CHROME_ORIGINS_SEEN_SERVICE_FACTORY_H_
+#define IOS_CHROME_BROWSER_METRICS_IOS_CHROME_ORIGINS_SEEN_SERVICE_FACTORY_H_
+
+#include <memory>
+
+#include "base/macros.h"
+#include "components/keyed_service/ios/browser_state_keyed_service_factory.h"
+
+namespace base {
+template <typename T>
+struct DefaultSingletonTraits;
+}
+
+namespace ios {
+class ChromeBrowserState;
+}
+
+namespace navigation_metrics {
+class OriginsSeenService;
+}
+
+// Singleton that owns all OriginsSeenService and associates them with
+// ios::ChromeBrowserState.
+class IOSChromeOriginsSeenServiceFactory
+    : public BrowserStateKeyedServiceFactory {
+ public:
+  static navigation_metrics::OriginsSeenService* GetForBrowserState(
+      ios::ChromeBrowserState* browser_state);
+  static IOSChromeOriginsSeenServiceFactory* GetInstance();
+
+ private:
+  friend struct base::DefaultSingletonTraits<
+      IOSChromeOriginsSeenServiceFactory>;
+
+  IOSChromeOriginsSeenServiceFactory();
+  ~IOSChromeOriginsSeenServiceFactory() override;
+
+  // BrowserStateKeyedServiceFactory implementation.
+  std::unique_ptr<KeyedService> BuildServiceInstanceFor(
+      web::BrowserState* context) const override;
+  web::BrowserState* GetBrowserStateToUse(
+      web::BrowserState* context) const override;
+
+  DISALLOW_COPY_AND_ASSIGN(IOSChromeOriginsSeenServiceFactory);
+};
+
+#endif  // IOS_CHROME_BROWSER_METRICS_IOS_CHROME_ORIGINS_SEEN_SERVICE_FACTORY_H_