[translate] Add translate ranker model loader.

ios/chrome/browser/translate/translate_ranker_metrics_provider.cc

Index: ios/chrome/browser/translate/translate_ranker_metrics_provider.cc
diff --git a/ios/chrome/browser/translate/translate_ranker_metrics_provider.cc b/ios/chrome/browser/translate/translate_ranker_metrics_provider.cc
new file mode 100644
index 0000000000000000000000000000000000000000..4c1d40ba51ca1774a638c96bbd5407faa1e01415
--- /dev/null
+++ b/ios/chrome/browser/translate/translate_ranker_metrics_provider.cc
@@ -0,0 +1,39 @@
+// 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 "ios/chrome/browser/translate/translate_ranker_metrics_provider.h"
+
+#include "components/metrics/proto/chrome_user_metrics_extension.pb.h"
+#include "components/metrics/proto/translate_event.pb.h"
+#include "components/translate/core/browser/translate_ranker.h"
+#include "ios/chrome/browser/application_context.h"
+#include "ios/chrome/browser/browser_state/chrome_browser_state.h"
+#include "ios/chrome/browser/browser_state/chrome_browser_state_manager.h"
+#include "ios/chrome/browser/translate/translate_ranker_factory.h"
+#include "ios/web/public/browser_state.h"
+
+namespace translate {
+
+void TranslateRankerMetricsProvider::ProvideGeneralMetrics(
+    metrics::ChromeUserMetricsExtension* uma_proto) {
+  std::vector<ios::ChromeBrowserState*> browser_states =
+      GetApplicationContext()
+          ->GetChromeBrowserStateManager()
+          ->GetLoadedBrowserStates();
+  for (auto* state : browser_states) {
+    TranslateRanker* ranker =
+        TranslateRankerFactory::GetInstance()->GetForBrowserState(state);
+    if (!ranker)
+      continue;
+
+    std::vector<std::unique_ptr<metrics::TranslateEventProto>> translate_events;
+    ranker->FlushTranslateEvents(&translate_events);
+
+    for (auto& event : translate_events) {
+      uma_proto->add_translate_event()->Swap(event.get());
+    }
+  }
+}
+
+}  // namespace translate