Componentize OriginsSeenService & provide iOS factory.

components/navigation_metrics/origins_seen_service.cc

Index: components/navigation_metrics/origins_seen_service.cc
diff --git a/chrome/browser/tab_contents/origins_seen_service.cc b/components/navigation_metrics/origins_seen_service.cc
similarity index 80%
rename from chrome/browser/tab_contents/origins_seen_service.cc
rename to components/navigation_metrics/origins_seen_service.cc
index 7d3736650663bb83bcccc2bbc07bcaa9ddfef923..b6bab64f22583169ffe89d9b661f64f73c0b0646 100644
--- a/chrome/browser/tab_contents/origins_seen_service.cc
+++ b/components/navigation_metrics/origins_seen_service.cc
@@ -2,8 +2,9 @@
 // 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.h"
+#include "components/navigation_metrics/origins_seen_service.h"
 
+namespace navigation_metrics {
 namespace {
 const size_t kDefaultMRUCacheSize = 1000;
 }  // namespace
@@ -18,3 +19,4 @@ bool OriginsSeenService::Insert(const url::Origin& origin) {
   origins_seen_.Put(origin, true);
   return seen;
 }
+}  // namespace navigation_metrics