[NTP Snippets] Clean up NTPSnippetsFetcher

components/ntp_snippets/remote/ntp_snippets_fetcher_unittest.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 "components/ntp_snippets/remote/ntp_snippets_fetcher.h"
 
 #include <map>
 #include <utility>
 
 #include "base/json/json_reader.h"
@@ skipping 177 matching lines @@
   MockSnippetsAvailableCallback& mock_callback() { return mock_callback_; }
   void FastForwardUntilNoTasksRemain() {
     mock_task_runner_->FastForwardUntilNoTasksRemain();
   }
   const std::string& test_lang() const { return test_lang_; }
   const GURL& test_url() { return test_url_; }
   const std::set<std::string>& test_hosts() const { return test_hosts_; }
   const std::set<std::string>& test_excluded() const { return test_excluded_; }
   base::HistogramTester& histogram_tester() { return histogram_tester_; }
 
+  NTPSnippetsFetcher::Params test_params() {
+    NTPSnippetsFetcher::Params result;
+    result.hosts = test_hosts();
+    result.language_code = test_lang();
+    result.excluded_ids = test_excluded();
+    result.count_to_fetch = 1;
+    result.interactive_request = true;
+    return result;
+  }
+
   void InitFakeURLFetcherFactory() {
     if (fake_url_fetcher_factory_)
       return;
     // Instantiation of factory automatically sets itself as URLFetcher's
     // factory.
     fake_url_fetcher_factory_.reset(new net::FakeURLFetcherFactory(
         /*default_factory=*/&failing_url_fetcher_factory_));
   }
 
   void SetFakeResponse(const std::string& response_data,
@@ skipping 31 matching lines @@
 
 class NTPSnippetsContentSuggestionsFetcherTest : public NTPSnippetsFetcherTest {
  public:
   NTPSnippetsContentSuggestionsFetcherTest()
       : NTPSnippetsFetcherTest(
             GURL(kTestChromeContentSuggestionsUrl),
             {{"content_suggestions_backend", kContentSuggestionsServer}}) {}
 };
 
 TEST_F(NTPSnippetsFetcherTest, BuildRequestAuthenticated) {
-  NTPSnippetsFetcher::RequestParams params;
-  params.obfuscated_gaia_id = "0BFUSGAIA";
-  params.only_return_personalized_results = true;
-  params.user_locale = "en";
-  params.host_restricts = {"chromium.org"};
-  params.excluded_ids = {"1234567890"};
-  params.count_to_fetch = 25;
-  params.interactive_request = false;
-  params.user_class = "ACTIVE_NTP_USER";
+  NTPSnippetsFetcher::RequestBuilder builder;
+  builder.params.hosts = {"chromium.org"};
+  builder.params.excluded_ids = {"1234567890"};
+  builder.params.count_to_fetch = 25;
+  builder.params.language_code = "en";
+  builder.params.interactive_request = false;
+  builder.obfuscated_gaia_id = "0BFUSGAIA";
+  builder.only_return_personalized_results = true;
+  builder.user_class = "ACTIVE_NTP_USER";
 
-
-  params.fetch_api = NTPSnippetsFetcher::CHROME_READER_API;
-  EXPECT_THAT(params.BuildRequest(),
+  builder.fetch_api = NTPSnippetsFetcher::CHROME_READER_API;
+  EXPECT_THAT(builder.BuildRequest(),
               EqualsJSON("{"
                          "  \"response_detail_level\": \"STANDARD\","
                          "  \"obfuscated_gaia_id\": \"0BFUSGAIA\","
                          "  \"user_locale\": \"en\","
                          "  \"advanced_options\": {"
                          "    \"local_scoring_params\": {"
                          "      \"content_params\": {"
                          "        \"only_return_personalized_results\": true"
                          "      },"
                          "      \"content_restricts\": ["
@@ skipping 17 matching lines @@
                          "        }"
                          "      ]"
                          "    },"
                          "    \"global_scoring_params\": {"
                          "      \"num_to_return\": 25,"
                          "      \"sort_type\": 1"
                          "    }"
                          "  }"
                          "}"));
 
-  params.fetch_api = NTPSnippetsFetcher::CHROME_CONTENT_SUGGESTIONS_API;
-  EXPECT_THAT(params.BuildRequest(),
+  builder.fetch_api = NTPSnippetsFetcher::CHROME_CONTENT_SUGGESTIONS_API;
+  EXPECT_THAT(builder.BuildRequest(),
               EqualsJSON("{"
                          "  \"uiLanguage\": \"en\","
                          "  \"priority\": \"BACKGROUND_PREFETCH\","
                          "  \"regularlyVisitedHostNames\": ["
                          "    \"chromium.org\""
                          "  ],"
                          "  \"excludedSuggestionIds\": ["
                          "    \"1234567890\""
                          "  ],"
                          "  \"userActivenessClass\": \"ACTIVE_NTP_USER\""
                          "}"));
 }
 
 TEST_F(NTPSnippetsFetcherTest, BuildRequestUnauthenticated) {
-  NTPSnippetsFetcher::RequestParams params;
-  params.only_return_personalized_results = false;
-  params.host_restricts = {};
-  params.count_to_fetch = 10;
-  params.excluded_ids = {};
-  params.interactive_request = true;
-  params.user_class = "ACTIVE_NTP_USER";
+  NTPSnippetsFetcher::RequestBuilder builder;
+  builder.params = test_params();
+  builder.only_return_personalized_results = false;
+  builder.user_class = "ACTIVE_NTP_USER";
 
-  params.fetch_api = NTPSnippetsFetcher::CHROME_READER_API;
-  EXPECT_THAT(params.BuildRequest(),
+  builder.fetch_api = NTPSnippetsFetcher::CHROME_READER_API;
+  EXPECT_THAT(builder.BuildRequest(),
               EqualsJSON("{"
                          "  \"response_detail_level\": \"STANDARD\","
                          "  \"advanced_options\": {"
                          "    \"local_scoring_params\": {"
                          "      \"content_params\": {"
                          "        \"only_return_personalized_results\": false"
                          "      },"
                          "      \"content_restricts\": ["
                          "        {"
                          "          \"type\": \"METADATA\","
@@ skipping 10 matching lines @@
                          "      ],"
                          "      \"content_selectors\": []"
                          "    },"
                          "    \"global_scoring_params\": {"
                          "      \"num_to_return\": 10,"
                          "      \"sort_type\": 1"
                          "    }"
                          "  }"
                          "}"));
 
-  params.fetch_api = NTPSnippetsFetcher::CHROME_CONTENT_SUGGESTIONS_API;
-  EXPECT_THAT(params.BuildRequest(),
+  builder.fetch_api = NTPSnippetsFetcher::CHROME_CONTENT_SUGGESTIONS_API;
+  EXPECT_THAT(builder.BuildRequest(),
               EqualsJSON("{"
                          "  \"regularlyVisitedHostNames\": [],"
                          "  \"priority\": \"USER_ACTION\","
                          "  \"excludedSuggestionIds\": [],"
                          "  \"userActivenessClass\": \"ACTIVE_NTP_USER\""
                          "}"));
 }
 
 TEST_F(NTPSnippetsFetcherTest, BuildRequestExcludedIds) {
-  NTPSnippetsFetcher::RequestParams params;
-  params.only_return_personalized_results = false;
-  params.host_restricts = {};
-  params.count_to_fetch = 10;
-  params.interactive_request = false;
-  for (int i = 0; i < 200; ++i) {
-    params.excluded_ids.insert(base::StringPrintf("%03d", i));
-  }
-  params.user_class = "ACTIVE_NTP_USER";
+  NTPSnippetsFetcher::RequestBuilder builder;
+  builder.params = test_params();
+  for (int i = 0; i < 200; ++i)
+    builder.params.excluded_ids.insert(base::StringPrintf("%03d", i));
+  builder.only_return_personalized_results = false;
+  builder.user_class = "ACTIVE_NTP_USER";
 
-  params.fetch_api = NTPSnippetsFetcher::CHROME_CONTENT_SUGGESTIONS_API;
-  EXPECT_THAT(params.BuildRequest(),
+  builder.fetch_api = NTPSnippetsFetcher::CHROME_CONTENT_SUGGESTIONS_API;
+  EXPECT_THAT(builder.BuildRequest(),
               EqualsJSON("{"
                          "  \"regularlyVisitedHostNames\": [],"
                          "  \"priority\": \"BACKGROUND_PREFETCH\","
                          "  \"excludedSuggestionIds\": ["
                          "    \"000\", \"001\", \"002\", \"003\", \"004\","
                          "    \"005\", \"006\", \"007\", \"008\", \"009\","
                          "    \"010\", \"011\", \"012\", \"013\", \"014\","
                          "    \"015\", \"016\", \"017\", \"018\", \"019\","
                          "    \"020\", \"021\", \"022\", \"023\", \"024\","
                          "    \"025\", \"026\", \"027\", \"028\", \"029\","
@@ skipping 12 matching lines @@
                          "    \"090\", \"091\", \"092\", \"093\", \"094\","
                          "    \"095\", \"096\", \"097\", \"098\", \"099\""
                          // Truncated to 100 entries. Currently, they happen to
                          // be those lexically first.
                          "  ],"
                          "  \"userActivenessClass\": \"ACTIVE_NTP_USER\""
                          "}"));
 }
 
 TEST_F(NTPSnippetsFetcherTest, BuildRequestNoUserClass) {
-  NTPSnippetsFetcher::RequestParams params;
-  params.only_return_personalized_results = false;
-  params.host_restricts = {};
-  params.count_to_fetch = 10;
-  params.interactive_request = false;
+  NTPSnippetsFetcher::RequestBuilder builder;
+  builder.params = test_params();
+  builder.only_return_personalized_results = false;
 
-  params.fetch_api = NTPSnippetsFetcher::CHROME_CONTENT_SUGGESTIONS_API;
-  EXPECT_THAT(params.BuildRequest(),
+  builder.fetch_api = NTPSnippetsFetcher::CHROME_CONTENT_SUGGESTIONS_API;
+  EXPECT_THAT(builder.BuildRequest(),
               EqualsJSON("{"
                          "  \"regularlyVisitedHostNames\": [],"
                          "  \"priority\": \"BACKGROUND_PREFETCH\","
                          "  \"excludedSuggestionIds\": []"
                          "}"));
 }
 
 TEST_F(NTPSnippetsFetcherTest, BuildRequestWithTwoLanguages) {
-  NTPSnippetsFetcher::RequestParams params;
-  params.only_return_personalized_results = false;
-  params.host_restricts = {};
-  params.count_to_fetch = 10;
-  params.interactive_request = true;
-  params.ui_language.language_code = "en";
-  params.ui_language.frequency = 0.5f;
-  params.other_top_language.language_code = "de";
-  params.other_top_language.frequency = 0.5f;
+  NTPSnippetsFetcher::RequestBuilder builder;
+  builder.params = test_params();
+  builder.params.interactive_request = true;
+  builder.only_return_personalized_results = false;
+  builder.ui_language.language_code = "en";
+  builder.ui_language.frequency = 0.5f;
+  builder.other_top_language.language_code = "de";
+  builder.other_top_language.frequency = 0.5f;
 
-  params.fetch_api = NTPSnippetsFetcher::CHROME_CONTENT_SUGGESTIONS_API;
-  EXPECT_THAT(params.BuildRequest(),
+  builder.fetch_api = NTPSnippetsFetcher::CHROME_CONTENT_SUGGESTIONS_API;
+  EXPECT_THAT(builder.BuildRequest(),
               EqualsJSON("{"
                          "  \"regularlyVisitedHostNames\": [],"
                          "  \"priority\": \"USER_ACTION\","
                          "  \"excludedSuggestionIds\": [],"
                          "  \"topLanguages\": ["
                          "    {"
                          "      \"language\" : \"en\","
                          "      \"frequency\" : 0.5"
                          "    },"
                          "    {"
                          "      \"language\" : \"de\","
                          "      \"frequency\" : 0.5"
                          "    }"
                          "  ]"
                          "}"));
 }
 
 TEST_F(NTPSnippetsFetcherTest, BuildRequestWithUILanguageOnly) {
-  NTPSnippetsFetcher::RequestParams params;
-  params.only_return_personalized_results = false;
-  params.host_restricts = {};
-  params.count_to_fetch = 10;
-  params.interactive_request = true;
-  params.ui_language.language_code = "en";
-  params.ui_language.frequency = 0.5f;
+  NTPSnippetsFetcher::RequestBuilder builder;
+  builder.params = test_params();
+  builder.params.interactive_request = true;
+  builder.only_return_personalized_results = false;
+  builder.ui_language.language_code = "en";
+  builder.ui_language.frequency = 0.5f;
 
-  params.fetch_api = NTPSnippetsFetcher::CHROME_CONTENT_SUGGESTIONS_API;
-  EXPECT_THAT(params.BuildRequest(),
+  builder.fetch_api = NTPSnippetsFetcher::CHROME_CONTENT_SUGGESTIONS_API;
+  EXPECT_THAT(builder.BuildRequest(),
               EqualsJSON("{"
                          "  \"regularlyVisitedHostNames\": [],"
                          "  \"priority\": \"USER_ACTION\","
                          "  \"excludedSuggestionIds\": [],"
                          "  \"topLanguages\": [{"
                          "    \"language\" : \"en\","
                          "    \"frequency\" : 0.5"
                          "  }]"
                          "}"));
 }
 
 TEST_F(NTPSnippetsFetcherTest, BuildRequestWithOtherLanguageOnly) {
-  NTPSnippetsFetcher::RequestParams params;
-  params.only_return_personalized_results = false;
-  params.host_restricts = {};
-  params.count_to_fetch = 10;
-  params.interactive_request = true;
-  params.other_top_language.language_code = "de";
-  params.other_top_language.frequency = 0.5f;
+  NTPSnippetsFetcher::RequestBuilder builder;
+  builder.params = test_params();
+  builder.params.interactive_request = true;
+  builder.only_return_personalized_results = false;
+  builder.other_top_language.language_code = "de";
+  builder.other_top_language.frequency = 0.5f;
 
-  params.fetch_api = NTPSnippetsFetcher::CHROME_CONTENT_SUGGESTIONS_API;
-  EXPECT_THAT(params.BuildRequest(),
+  builder.fetch_api = NTPSnippetsFetcher::CHROME_CONTENT_SUGGESTIONS_API;
+  EXPECT_THAT(builder.BuildRequest(),
               EqualsJSON("{"
                          "  \"regularlyVisitedHostNames\": [],"
                          "  \"priority\": \"USER_ACTION\","
                          "  \"excludedSuggestionIds\": [],"
                          "  \"topLanguages\": [{"
                          "    \"language\" : \"de\","
                          "    \"frequency\" : 0.5"
                          "  }]"
                          "}"));
 }
@@ skipping 17 matching lines @@
       "    \"sourceCorpusInfo\" : [{"
       "      \"ampUrl\" : \"http://localhost/amp\","
       "      \"corpusId\" : \"http://localhost/foobar\","
       "      \"publisherData\": { \"sourceName\" : \"Foo News\" }"
       "    }]"
       "  }"
       "}]}";
   SetFakeResponse(/*response_data=*/kJsonStr, net::HTTP_OK,
                   net::URLRequestStatus::SUCCESS);
   EXPECT_CALL(mock_callback(), Run(IsSingleArticle("http://localhost/foobar")));
-  snippets_fetcher().FetchSnippetsFromHosts(test_hosts(), test_lang(),
-                                            test_excluded(),
-                                            /*count=*/1,
-                                            /*interactive_request=*/true);
+  snippets_fetcher().FetchSnippets(test_params());
   FastForwardUntilNoTasksRemain();
   EXPECT_THAT(snippets_fetcher().last_status(), Eq("OK"));
   EXPECT_THAT(snippets_fetcher().last_json(), Eq(kJsonStr));
   EXPECT_THAT(histogram_tester().GetAllSamples(
                   "NewTabPage.Snippets.FetchHttpResponseOrErrorCode"),
               ElementsAre(base::Bucket(/*min=*/200, /*count=*/1)));
   EXPECT_THAT(histogram_tester().GetAllSamples("NewTabPage.Snippets.FetchTime"),
               ElementsAre(base::Bucket(/*min=*/kTestJsonParsingLatencyMs,
                                        /*count=*/1)));
 }
@@ skipping 12 matching lines @@
       "    \"expirationTime\" : \"2016-07-01T11:01:37.000Z\","
       "    \"attribution\" : \"Foo News\","
       "    \"imageUrl\" : \"http://localhost/foobar.jpg\","
       "    \"ampUrl\" : \"http://localhost/amp\","
       "    \"faviconUrl\" : \"http://localhost/favicon.ico\" "
       "  }]"
       "}]}";
   SetFakeResponse(/*response_data=*/kJsonStr, net::HTTP_OK,
                   net::URLRequestStatus::SUCCESS);
   EXPECT_CALL(mock_callback(), Run(IsSingleArticle("http://localhost/foobar")));
-  snippets_fetcher().FetchSnippetsFromHosts(test_hosts(), test_lang(),
-                                            test_excluded(),
-                                            /*count=*/1,
-                                            /*interactive_request=*/true);
+  snippets_fetcher().FetchSnippets(test_params());
   FastForwardUntilNoTasksRemain();
   EXPECT_THAT(snippets_fetcher().last_status(), Eq("OK"));
   EXPECT_THAT(snippets_fetcher().last_json(), Eq(kJsonStr));
   EXPECT_THAT(histogram_tester().GetAllSamples(
                   "NewTabPage.Snippets.FetchHttpResponseOrErrorCode"),
               ElementsAre(base::Bucket(/*min=*/200, /*count=*/1)));
   EXPECT_THAT(histogram_tester().GetAllSamples("NewTabPage.Snippets.FetchTime"),
               ElementsAre(base::Bucket(/*min=*/kTestJsonParsingLatencyMs,
                                        /*count=*/1)));
 }
 
 TEST_F(NTPSnippetsContentSuggestionsFetcherTest, EmptyCategoryIsOK) {
   const std::string kJsonStr =
       "{\"categories\" : [{"
       "  \"id\": 1,"
       "  \"localizedTitle\": \"Articles for You\""
       "}]}";
   SetFakeResponse(/*response_data=*/kJsonStr, net::HTTP_OK,
                   net::URLRequestStatus::SUCCESS);
   EXPECT_CALL(mock_callback(), Run(IsEmptyArticleList()));
-  snippets_fetcher().FetchSnippetsFromHosts(test_hosts(), test_lang(),
-                                            test_excluded(),
-                                            /*count=*/1,
-                                            /*interactive_request=*/true);
+  snippets_fetcher().FetchSnippets(test_params());
   FastForwardUntilNoTasksRemain();
   EXPECT_THAT(snippets_fetcher().last_status(), Eq("OK"));
   EXPECT_THAT(snippets_fetcher().last_json(), Eq(kJsonStr));
   EXPECT_THAT(histogram_tester().GetAllSamples(
                   "NewTabPage.Snippets.FetchHttpResponseOrErrorCode"),
               ElementsAre(base::Bucket(/*min=*/200, /*count=*/1)));
   EXPECT_THAT(histogram_tester().GetAllSamples("NewTabPage.Snippets.FetchTime"),
               ElementsAre(base::Bucket(/*min=*/kTestJsonParsingLatencyMs,
                                        /*count=*/1)));
 }
@@ skipping 29 matching lines @@
       "    \"imageUrl\" : \"http://localhost/foo2.jpg\","
       "    \"ampUrl\" : \"http://localhost/amp\","
       "    \"faviconUrl\" : \"http://localhost/favicon.ico\" "
       "  }]"
       "}]}";
   SetFakeResponse(/*response_data=*/kJsonStr, net::HTTP_OK,
                   net::URLRequestStatus::SUCCESS);
   NTPSnippetsFetcher::OptionalFetchedCategories fetched_categories;
   EXPECT_CALL(mock_callback(), Run(_))
       .WillOnce(WithArg<0>(MovePointeeTo(&fetched_categories)));
-  snippets_fetcher().FetchSnippetsFromHosts(test_hosts(), test_lang(),
-                                            test_excluded(),
-                                            /*count=*/1,
-                                            /*interactive_request=*/true);
+  snippets_fetcher().FetchSnippets(test_params());
   FastForwardUntilNoTasksRemain();
 
   ASSERT_TRUE(fetched_categories);
   ASSERT_THAT(fetched_categories->size(), Eq(2u));
   for (const auto& category : *fetched_categories) {
     const auto& articles = category.snippets;
     switch (category.category.id()) {
       case static_cast<int>(KnownCategories::ARTICLES):
         ASSERT_THAT(articles.size(), Eq(1u));
         EXPECT_THAT(articles[0]->best_source().url.spec(),
@@ skipping 17 matching lines @@
   EXPECT_THAT(histogram_tester().GetAllSamples("NewTabPage.Snippets.FetchTime"),
               ElementsAre(base::Bucket(/*min=*/kTestJsonParsingLatencyMs,
                                        /*count=*/1)));
 }
 
 TEST_F(NTPSnippetsFetcherTest, ShouldFetchSuccessfullyEmptyList) {
   const std::string kJsonStr = "{\"recos\": []}";
   SetFakeResponse(/*response_data=*/kJsonStr, net::HTTP_OK,
                   net::URLRequestStatus::SUCCESS);
   EXPECT_CALL(mock_callback(), Run(IsEmptyArticleList()));
-  snippets_fetcher().FetchSnippetsFromHosts(test_hosts(), test_lang(),
-                                            test_excluded(),
-                                            /*count=*/1,
-                                            /*interactive_request=*/true);
+  snippets_fetcher().FetchSnippets(test_params());
   FastForwardUntilNoTasksRemain();
   EXPECT_THAT(snippets_fetcher().last_status(), Eq("OK"));
   EXPECT_THAT(snippets_fetcher().last_json(), Eq(kJsonStr));
   EXPECT_THAT(
       histogram_tester().GetAllSamples("NewTabPage.Snippets.FetchResult"),
       ElementsAre(base::Bucket(/*min=*/0, /*count=*/1)));
   EXPECT_THAT(histogram_tester().GetAllSamples(
                   "NewTabPage.Snippets.FetchHttpResponseOrErrorCode"),
               ElementsAre(base::Bucket(/*min=*/200, /*count=*/1)));
 }
 
 TEST_F(NTPSnippetsFetcherTest, ShouldRestrictToHosts) {
   net::TestURLFetcherFactory test_url_fetcher_factory;
-  snippets_fetcher().FetchSnippetsFromHosts(
-      {"www.somehost1.com", "www.somehost2.com"}, test_lang(), test_excluded(),
-      /*count=*/17,
-      /*interactive_request=*/true);
+  NTPSnippetsFetcher::Params params = test_params();
+  params.hosts = {"www.somehost1.com", "www.somehost2.com"};
+  params.count_to_fetch = 17;
+  snippets_fetcher().FetchSnippets(params);
   net::TestURLFetcher* fetcher = test_url_fetcher_factory.GetFetcherByID(0);
   ASSERT_THAT(fetcher, NotNull());
   std::unique_ptr<base::Value> value =
       base::JSONReader::Read(fetcher->upload_data());
   ASSERT_TRUE(value) << " failed to parse JSON: "
                      << PrintToString(fetcher->upload_data());
   const base::DictionaryValue* dict = nullptr;
   ASSERT_TRUE(value->GetAsDictionary(&dict));
   const base::DictionaryValue* local_scoring_params = nullptr;
   ASSERT_TRUE(dict->GetDictionary("advanced_options.local_scoring_params",
                                   &local_scoring_params));
   const base::ListValue* content_selectors = nullptr;
   ASSERT_TRUE(
       local_scoring_params->GetList("content_selectors", &content_selectors));
   ASSERT_THAT(content_selectors->GetSize(), Eq(static_cast<size_t>(2)));
   const base::DictionaryValue* content_selector = nullptr;
   ASSERT_TRUE(content_selectors->GetDictionary(0, &content_selector));
   std::string content_selector_value;
   EXPECT_TRUE(content_selector->GetString("value", &content_selector_value));
   EXPECT_THAT(content_selector_value, Eq("www.somehost1.com"));
   ASSERT_TRUE(content_selectors->GetDictionary(1, &content_selector));
   EXPECT_TRUE(content_selector->GetString("value", &content_selector_value));
   EXPECT_THAT(content_selector_value, Eq("www.somehost2.com"));
 }
 
 TEST_F(NTPSnippetsFetcherTest, ShouldReportUrlStatusError) {
   SetFakeResponse(/*response_data=*/std::string(), net::HTTP_NOT_FOUND,
                   net::URLRequestStatus::FAILED);
   EXPECT_CALL(mock_callback(), Run(/*snippets=*/Not(HasValue()))).Times(1);
-  snippets_fetcher().FetchSnippetsFromHosts(test_hosts(), test_lang(),
-                                            test_excluded(),
-                                            /*count=*/1,
-                                            /*interactive_request=*/true);
+  snippets_fetcher().FetchSnippets(test_params());
   FastForwardUntilNoTasksRemain();
   EXPECT_THAT(snippets_fetcher().last_status(),
               Eq("URLRequestStatus error -2"));
   EXPECT_THAT(snippets_fetcher().last_json(), IsEmpty());
   EXPECT_THAT(
       histogram_tester().GetAllSamples("NewTabPage.Snippets.FetchResult"),
       ElementsAre(base::Bucket(/*min=*/2, /*count=*/1)));
   EXPECT_THAT(histogram_tester().GetAllSamples(
                   "NewTabPage.Snippets.FetchHttpResponseOrErrorCode"),
               ElementsAre(base::Bucket(/*min=*/-2, /*count=*/1)));
   EXPECT_THAT(histogram_tester().GetAllSamples("NewTabPage.Snippets.FetchTime"),
               Not(IsEmpty()));
 }
 
 TEST_F(NTPSnippetsFetcherTest, ShouldReportHttpError) {
   SetFakeResponse(/*response_data=*/std::string(), net::HTTP_NOT_FOUND,
                   net::URLRequestStatus::SUCCESS);
   EXPECT_CALL(mock_callback(), Run(/*snippets=*/Not(HasValue()))).Times(1);
-  snippets_fetcher().FetchSnippetsFromHosts(test_hosts(), test_lang(),
-                                            test_excluded(),
-                                            /*count=*/1,
-                                            /*interactive_request=*/true);
+  snippets_fetcher().FetchSnippets(test_params());
   FastForwardUntilNoTasksRemain();
   EXPECT_THAT(snippets_fetcher().last_json(), IsEmpty());
   EXPECT_THAT(
       histogram_tester().GetAllSamples("NewTabPage.Snippets.FetchResult"),
       ElementsAre(base::Bucket(/*min=*/3, /*count=*/1)));
   EXPECT_THAT(histogram_tester().GetAllSamples(
                   "NewTabPage.Snippets.FetchHttpResponseOrErrorCode"),
               ElementsAre(base::Bucket(/*min=*/404, /*count=*/1)));
   EXPECT_THAT(histogram_tester().GetAllSamples("NewTabPage.Snippets.FetchTime"),
               Not(IsEmpty()));
 }
 
 TEST_F(NTPSnippetsFetcherTest, ShouldReportJsonError) {
   const std::string kInvalidJsonStr = "{ \"recos\": []";
   SetFakeResponse(/*response_data=*/kInvalidJsonStr, net::HTTP_OK,
                   net::URLRequestStatus::SUCCESS);
   EXPECT_CALL(mock_callback(), Run(/*snippets=*/Not(HasValue()))).Times(1);
-  snippets_fetcher().FetchSnippetsFromHosts(test_hosts(), test_lang(),
-                                            test_excluded(),
-                                            /*count=*/1,
-                                            /*interactive_request=*/true);
+  snippets_fetcher().FetchSnippets(test_params());
   FastForwardUntilNoTasksRemain();
   EXPECT_THAT(snippets_fetcher().last_status(),
               StartsWith("Received invalid JSON (error "));
   EXPECT_THAT(snippets_fetcher().last_json(), Eq(kInvalidJsonStr));
   EXPECT_THAT(
       histogram_tester().GetAllSamples("NewTabPage.Snippets.FetchResult"),
       ElementsAre(base::Bucket(/*min=*/4, /*count=*/1)));
   EXPECT_THAT(histogram_tester().GetAllSamples(
                   "NewTabPage.Snippets.FetchHttpResponseOrErrorCode"),
               ElementsAre(base::Bucket(/*min=*/200, /*count=*/1)));
   EXPECT_THAT(histogram_tester().GetAllSamples("NewTabPage.Snippets.FetchTime"),
               ElementsAre(base::Bucket(/*min=*/kTestJsonParsingLatencyMs,
                                        /*count=*/1)));
 }
 
 TEST_F(NTPSnippetsFetcherTest, ShouldReportJsonErrorForEmptyResponse) {
   SetFakeResponse(/*response_data=*/std::string(), net::HTTP_OK,
                   net::URLRequestStatus::SUCCESS);
   EXPECT_CALL(mock_callback(), Run(/*snippets=*/Not(HasValue()))).Times(1);
-  snippets_fetcher().FetchSnippetsFromHosts(test_hosts(), test_lang(),
-                                            test_excluded(),
-                                            /*count=*/1,
-                                            /*interactive_request=*/true);
+  snippets_fetcher().FetchSnippets(test_params());
   FastForwardUntilNoTasksRemain();
   EXPECT_THAT(snippets_fetcher().last_json(), std::string());
   EXPECT_THAT(
       histogram_tester().GetAllSamples("NewTabPage.Snippets.FetchResult"),
       ElementsAre(base::Bucket(/*min=*/4, /*count=*/1)));
   EXPECT_THAT(histogram_tester().GetAllSamples(
                   "NewTabPage.Snippets.FetchHttpResponseOrErrorCode"),
               ElementsAre(base::Bucket(/*min=*/200, /*count=*/1)));
 }
 
 TEST_F(NTPSnippetsFetcherTest, ShouldReportInvalidListError) {
   const std::string kJsonStr =
       "{\"recos\": [{ \"contentInfo\": { \"foo\" : \"bar\" }}]}";
   SetFakeResponse(/*response_data=*/kJsonStr, net::HTTP_OK,
                   net::URLRequestStatus::SUCCESS);
   EXPECT_CALL(mock_callback(), Run(/*snippets=*/Not(HasValue()))).Times(1);
-  snippets_fetcher().FetchSnippetsFromHosts(test_hosts(), test_lang(),
-                                            test_excluded(),
-                                            /*count=*/1,
-                                            /*interactive_request=*/true);
+  snippets_fetcher().FetchSnippets(test_params());
   FastForwardUntilNoTasksRemain();
   EXPECT_THAT(snippets_fetcher().last_json(), Eq(kJsonStr));
   EXPECT_THAT(
       histogram_tester().GetAllSamples("NewTabPage.Snippets.FetchResult"),
       ElementsAre(base::Bucket(/*min=*/5, /*count=*/1)));
   EXPECT_THAT(histogram_tester().GetAllSamples(
                   "NewTabPage.Snippets.FetchHttpResponseOrErrorCode"),
               ElementsAre(base::Bucket(/*min=*/200, /*count=*/1)));
   EXPECT_THAT(histogram_tester().GetAllSamples("NewTabPage.Snippets.FetchTime"),
               Not(IsEmpty()));
 }
 
 // This test actually verifies that the test setup itself is sane, to prevent
 // hard-to-reproduce test failures.
 TEST_F(NTPSnippetsFetcherTest, ShouldReportHttpErrorForMissingBakedResponse) {
   InitFakeURLFetcherFactory();
   EXPECT_CALL(mock_callback(), Run(/*snippets=*/Not(HasValue()))).Times(1);
-  snippets_fetcher().FetchSnippetsFromHosts(test_hosts(), test_lang(),
-                                            test_excluded(),
-                                            /*count=*/1,
-                                            /*interactive_request=*/true);
+  snippets_fetcher().FetchSnippets(test_params());
   FastForwardUntilNoTasksRemain();
 }
 
 TEST_F(NTPSnippetsFetcherTest, ShouldCancelOngoingFetch) {
   const std::string kJsonStr = "{ \"recos\": [] }";
   SetFakeResponse(/*response_data=*/kJsonStr, net::HTTP_OK,
                   net::URLRequestStatus::SUCCESS);
   EXPECT_CALL(mock_callback(), Run(IsEmptyArticleList()));
-  snippets_fetcher().FetchSnippetsFromHosts(test_hosts(), test_lang(),
-                                            test_excluded(),
-                                            /*count=*/1,
-                                            /*interactive_request=*/true);
-  // Second call to FetchSnippetsFromHosts() overrides/cancels the previous.
+  snippets_fetcher().FetchSnippets(test_params());
+  // Second call to FetchSnippets() overrides/cancels the previous.
   // Callback is expected to be called once.
-  snippets_fetcher().FetchSnippetsFromHosts(test_hosts(), test_lang(),
-                                            test_excluded(),
-                                            /*count=*/1,
-                                            /*interactive_request=*/true);
+  snippets_fetcher().FetchSnippets(test_params());
   FastForwardUntilNoTasksRemain();
   EXPECT_THAT(
       histogram_tester().GetAllSamples("NewTabPage.Snippets.FetchResult"),
       ElementsAre(base::Bucket(/*min=*/0, /*count=*/1)));
   EXPECT_THAT(histogram_tester().GetAllSamples(
                   "NewTabPage.Snippets.FetchHttpResponseOrErrorCode"),
               ElementsAre(base::Bucket(/*min=*/200, /*count=*/1)));
   EXPECT_THAT(histogram_tester().GetAllSamples("NewTabPage.Snippets.FetchTime"),
               ElementsAre(base::Bucket(/*min=*/kTestJsonParsingLatencyMs,
                                        /*count=*/1)));
 }
 
 ::std::ostream& operator<<(
     ::std::ostream& os,
     const NTPSnippetsFetcher::OptionalFetchedCategories& fetched_categories) {
   if (fetched_categories) {
     // Matchers above aren't any more precise than this, so this is sufficient
     // for test-failure diagnostics.
     return os << "list with " << fetched_categories->size() << " elements";
   }
   return os << "null";
 }
 
 }  // namespace ntp_snippets