[translate] Add ranker model proto and loader.

components/translate/core/browser/ranker_model_unittest.cc

+// Copyright 2017 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 "components/translate/core/browser/ranker_model.h"
+
+#include <memory>
+
+#include "base/memory/ptr_util.h"
+#include "base/time/time.h"
+#include "components/translate/core/browser/proto/ranker_model.pb.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace {
+
+using chrome_intelligence::RankerModel;
+
+const char kModelURL[] = "https://some.url.net/model";
+
+int64_t InSeconds(const base::Time t) {
+  return (t - base::Time()).InSeconds();
+}
+
+std::unique_ptr<RankerModel> NewModel(const std::string& model_url,
+                                      base::Time last_modified,
+                                      base::TimeDelta cache_duration) {
+  std::unique_ptr<RankerModel> model = base::MakeUnique<RankerModel>();
+  auto* metadata = model->mutable_proto()->mutable_metadata();
+  if (!model_url.empty())
+    metadata->set_source(model_url);
+  if (!last_modified.is_null())
+    metadata->set_last_modified_sec(InSeconds(last_modified));
+  if (!cache_duration.is_zero())
+    metadata->set_cache_duration_sec(cache_duration.InSeconds());
+
+  auto* translate = model->mutable_proto()->mutable_translate();
+  translate->set_version(1);
+
+  auto* logit = translate->mutable_logistic_regression_model();
+  logit->set_bias(0.1f);
+  logit->set_accept_ratio_weight(0.2f);
+  logit->set_decline_ratio_weight(0.3f);
+  logit->set_ignore_ratio_weight(0.4f);
+  return model;
+}
+
+}  // namespace
+
+TEST(RankerModelTest, Serialization) {
+  base::Time last_modified = base::Time::Now();
+  base::TimeDelta cache_duration = base::TimeDelta::FromDays(3);
+  std::unique_ptr<RankerModel> original_model =
+      NewModel(kModelURL, last_modified, cache_duration);
+  std::string original_model_str = original_model->SerializeAsString();
+  std::unique_ptr<RankerModel> serialized_model =
+      RankerModel::FromString(original_model_str);
+  std::string serialized_model_str = serialized_model->SerializeAsString();
+
+  EXPECT_EQ(serialized_model_str, original_model_str);
+  EXPECT_EQ(serialized_model->GetSourceURL(), kModelURL);
+  EXPECT_EQ(serialized_model->proto().metadata().last_modified_sec(),
+            InSeconds(last_modified));
+  EXPECT_EQ(serialized_model->proto().metadata().cache_duration_sec(),
+            cache_duration.InSeconds());
+}
+
+TEST(RankerModelTest, IsExpired) {
+  base::Time today = base::Time::Now();
+  base::TimeDelta days_15 = base::TimeDelta::FromDays(15);
+  base::TimeDelta days_30 = base::TimeDelta::FromDays(30);
+  base::TimeDelta days_60 = base::TimeDelta::FromDays(60);
+
+  EXPECT_FALSE(NewModel(kModelURL, today, days_30)->IsExpired());
+  EXPECT_FALSE(NewModel(kModelURL, today - days_15, days_30)->IsExpired());
+  EXPECT_TRUE(NewModel(kModelURL, today - days_60, days_30)->IsExpired());
+}