[Zine] Update the referrer for Feed surfaces, make it configurable

* Updates referrer for content suggestions to https://feed.google.com
* Makes the referrer configurable through Field Trials bound to the
  NTPArticleSuggestions experiment.

Bug: 870750
Cq-Include-Trybots: luci.chromium.try:ios-simulator-full-configs;master.tryserver.chromium.mac:ios-simulator-cronet
Change-Id: I87b0af69e05e9b1c38bf12caade61ebb80f6cee0
Reviewed-on: https://chromium-review.googlesource.com/1185857
Commit-Queue: Filip Gorski <fgorski@chromium.org>
Reviewed-by: Peter Lee <pkl@chromium.org>
Reviewed-by: Theresa <twellington@chromium.org>
Cr-Commit-Position: refs/heads/master@{#586345}

chrome/android/java/src/org/chromium/chrome/browser/ChromeFeatureList.java

@@ -236,6 +236,7 @@ public abstract class ChromeFeatureList {
     public static final String NEW_PHOTO_PICKER = "NewPhotoPicker";
 
     public static final String NO_CREDIT_CARD_ABORT = "NoCreditCardAbort";
+    public static final String NTP_ARTICLE_SUGGESTIONS = "NTPArticleSuggestions";
     public static final String NTP_ARTICLE_SUGGESTIONS_EXPANDABLE_HEADER =
             "NTPArticleSuggestionsExpandableHeader";
     public static final String NTP_BUTTON = "NTPButton";

chrome/android/java/src/org/chromium/chrome/browser/suggestions/SuggestionsConfig.java

@@ -5,6 +5,7 @@
 package org.chromium.chrome.browser.suggestions;
 
 import android.content.res.Resources;
+import android.text.TextUtils;
 
 import org.chromium.base.ApiCompatibilityUtils;
 import org.chromium.chrome.R;
@@ -17,6 +18,18 @@ import org.chromium.chrome.browser.widget.displaystyle.UiConfig;
  * Provides configuration details for suggestions.
  */
 public final class SuggestionsConfig {
+    /**
+     * Field trial parameter for referrer URL.
+     * It must be kept in sync with //components/ntp_suggestions/features.cc
+     */
+    private static final String REFERRER_URL_PARAM = "referrer_url";
+
+    /**
+     * Default value for referrer URL.
+     * It must be kept in sync with //components/ntp_suggestions/features.cc
+     */
+    private static final String DEFAULT_REFERRER_URL = "https://feed.google.com/";
+
     private SuggestionsConfig() {}
 
     /**
@@ -67,4 +80,16 @@ public final class SuggestionsConfig {
         return FeatureUtilities.isChromeModernDesignEnabled()
                 || ChromeFeatureList.isEnabled(ChromeFeatureList.NTP_MODERN_LAYOUT);
     }
+
+    /** @return The value of referrer URL to use with content suggestions. */
+    public static String getReferrerUrl() {
+        String referrerParamValue = ChromeFeatureList.getFieldTrialParamByFeature(
+                ChromeFeatureList.NTP_ARTICLE_SUGGESTIONS, REFERRER_URL_PARAM);
+
+        if (!TextUtils.isEmpty(referrerParamValue)) {
+            return referrerParamValue;
+        }
+
+        return DEFAULT_REFERRER_URL;
+    }
 }

chrome/android/java/src/org/chromium/chrome/browser/suggestions/SuggestionsNavigationDelegateImpl.java

@@ -41,8 +41,6 @@ import org.chromium.ui.widget.Toast;
  * {@link SuggestionsUiDelegate} implementation.
  */
 public class SuggestionsNavigationDelegateImpl implements SuggestionsNavigationDelegate {
-    private static final String CHROME_CONTENT_SUGGESTIONS_REFERRER =
-            "https://www.googleapis.com/auth/chrome-content-suggestions";
     private static final String CHROME_CONTEXTUAL_SUGGESTIONS_REFERRER =
             "https://goto.google.com/explore-on-content-viewer";
     private static final String NEW_TAB_URL_HELP =
@@ -149,8 +147,8 @@ public class SuggestionsNavigationDelegateImpl implements SuggestionsNavigationD
         // to filter out these history entries for NTP tiles.
         // TODO(mastiz): Extend this with support for other categories.
         if (article.mCategory == KnownCategories.ARTICLES) {
-            loadUrlParams.setReferrer(new Referrer(CHROME_CONTENT_SUGGESTIONS_REFERRER,
-                    WebReferrerPolicy.ALWAYS));
+            loadUrlParams.setReferrer(
+                    new Referrer(SuggestionsConfig.getReferrerUrl(), WebReferrerPolicy.ALWAYS));
         }
 
         // Set appropriate referrer for contextual suggestions to distinguish them from navigation

chrome/browser/android/chrome_feature_list.cc

@@ -148,6 +148,7 @@ const base::Feature* kFeaturesExposedToJava[] = {
     &payments::features::kWebPaymentsSingleAppUiSkip,
     &media::kCafMediaRouterImpl,
     &ntp_snippets::kArticleSuggestionsExpandableHeader,
+    &ntp_snippets::kArticleSuggestionsFeature,
     &ntp_snippets::kIncreasedVisibility,
     &ntp_snippets::kForeignSessionsSuggestionsFeature,
     &ntp_snippets::kNotificationsFeature,

components/ntp_snippets/BUILD.gn

@@ -224,6 +224,7 @@ source_set("unit_tests") {
     "contextual/reporting/contextual_suggestions_composite_reporter_unittest.cc",
     "contextual/reporting/contextual_suggestions_metrics_reporter_unittest.cc",
     "contextual/reporting/contextual_suggestions_ukm_entry_unittest.cc",
+    "features_unittest.cc",
     "logger_unittest.cc",
     "reading_list/reading_list_suggestions_provider_unittest.cc",
     "remote/cached_image_fetcher_unittest.cc",

components/ntp_snippets/features.cc

@@ -5,6 +5,7 @@
 #include "components/ntp_snippets/features.h"
 
 #include "base/feature_list.h"
+#include "base/metrics/field_trial_params.h"
 #include "base/time/clock.h"
 #include "components/ntp_snippets/category_rankers/click_based_category_ranker.h"
 #include "components/ntp_snippets/category_rankers/constant_category_ranker.h"
@@ -166,4 +167,17 @@ std::vector<const base::Feature*> GetAllFeatures() {
       kAllFeatures, kAllFeatures + arraysize(kAllFeatures));
 }
 
+// Default referrer for the content suggestions.
+const char kDefaultReferrerUrl[] = "https://feed.google.com/";
+
+// Provides ability to customize the referrer URL.
+// When specifying a referrer through a field trial, it must contain a path.
+// In case of default value above the path is empty, but it is specified.
+base::FeatureParam<std::string> kArticleSuggestionsReferrerURLParam{
+    &kArticleSuggestionsFeature, "referrer_url", kDefaultReferrerUrl};
+
+std::string GetContentSuggestionsReferrerURL() {
+  return kArticleSuggestionsReferrerURLParam.Get();
+}
+
 }  // namespace ntp_snippets

components/ntp_snippets/features.h

@@ -140,6 +140,8 @@ extern const base::Feature kContentSuggestionsDebugLog;
 // Return all the features as a vector.
 std::vector<const base::Feature*> GetAllFeatures();
 
+// Return a referrer URL for content suggestions.
+std::string GetContentSuggestionsReferrerURL();
 }  // namespace ntp_snippets
 
 #endif  // COMPONENTS_NTP_SNIPPETS_FEATURES_H_

components/ntp_snippets/features_unittest.cc

+// Copyright 2018 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/features.h"
+
+#include <map>
+#include <string>
+
+#include "base/test/scoped_feature_list.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "url/gurl.h"
+
+namespace ntp_snippets {
+
+namespace {
+const char kTestFeedURL[] = "https://test.google.com/";
+}  // namespace
+
+TEST(FeaturesTest, GetContentSuggestionsReferrerURL_DefaultValue) {
+  base::test::ScopedFeatureList feature_list;
+  feature_list.InitAndEnableFeature(kArticleSuggestionsFeature);
+  EXPECT_EQ("https://feed.google.com/", GetContentSuggestionsReferrerURL());
+
+  // In code this will be often used inside of a GURL.
+  EXPECT_EQ("https://feed.google.com/",
+            GURL(GetContentSuggestionsReferrerURL()));
+  EXPECT_EQ("https://feed.google.com/",
+            GURL(GetContentSuggestionsReferrerURL()).spec());
+}
+
+TEST(FeaturesTest, GetContentSuggestionsReferrerURL_ParamValue) {
+  base::test::ScopedFeatureList feature_list;
+
+  std::map<std::string, std::string> parameters;
+  parameters["referrer_url"] = kTestFeedURL;
+  feature_list.InitAndEnableFeatureWithParameters(kArticleSuggestionsFeature,
+                                                  parameters);
+  EXPECT_EQ(kTestFeedURL, GetContentSuggestionsReferrerURL());
+}
+
+}  // namespace ntp_snippets

ios/chrome/browser/chrome_url_constants.cc

@@ -101,8 +101,5 @@ const char kGoogleHistoryURL[] = "https://history.google.com";
 const char kGoogleMyAccountURL[] =
     "https://myaccount.google.com/privacy#activitycontrols";
 
-const char kNewTabPageReferrerURL[] =
-    "chrome://do_not_consider_for_most_visited/new_tab_page";
-
 const char kReadingListReferrerURL[] =
     "chrome://do_not_consider_for_most_visited/reading_list";

ios/chrome/browser/chrome_url_constants.h

@@ -103,10 +103,6 @@ extern const char kGoogleHistoryURL[];
 // Google my account URL for the sign-in confirmation screen.
 extern const char kGoogleMyAccountURL[];
 
-// URL used in referrer to signal that the navigation originates from the New
-// Tab page and thus should not be considered for Most Visited.
-extern const char kNewTabPageReferrerURL[];
-
 // URL used in referrer to signal that the navigation originates from Reading
 // List page and thus should not be considered for Most Visited.
 extern const char kReadingListReferrerURL[];

ios/chrome/browser/history/BUILD.gn

@@ -49,6 +49,7 @@ source_set("tab_helper") {
     "//base",
     "//components/history/core/browser",
     "//components/keyed_service/core",
+    "//components/ntp_snippets",
     "//components/strings",
     "//ios/chrome/browser",
     "//ios/chrome/browser/browser_state",

ios/chrome/browser/history/history_tab_helper.mm

@@ -8,6 +8,7 @@
 #include "components/history/core/browser/history_constants.h"
 #include "components/history/core/browser/history_service.h"
 #include "components/keyed_service/core/service_access_type.h"
+#include "components/ntp_snippets/features.h"
 #include "components/strings/grit/components_strings.h"
 #include "ios/chrome/browser/browser_state/chrome_browser_state.h"
 #include "ios/chrome/browser/chrome_url_constants.h"
@@ -161,7 +162,7 @@ void HistoryTabHelper::DidFinishNavigation(
   // Navigations originating from New Tab Page or Reading List should not
   // contribute to Most Visited.
   const bool consider_for_ntp_most_visited =
-      referrer_url != kNewTabPageReferrerURL &&
+      referrer_url != ntp_snippets::GetContentSuggestionsReferrerURL() &&
       referrer_url != kReadingListReferrerURL;
 
   // Top-level frame navigations are visible; everything else is hidden.

ios/chrome/browser/ui/content_suggestions/ntp_home_mediator.mm

@@ -10,6 +10,7 @@
 #include "base/metrics/user_metrics.h"
 #include "base/metrics/user_metrics_action.h"
 #include "components/ntp_snippets/content_suggestions_service.h"
+#include "components/ntp_snippets/features.h"
 #include "components/strings/grit/components_strings.h"
 #include "ios/chrome/browser/chrome_url_constants.h"
 #import "ios/chrome/browser/metrics/new_tab_page_uma.h"
@@ -241,7 +242,8 @@ const char kRateThisAppCommand[] = "ratethisapp";
   // Use a referrer with a specific URL to mark this entry as coming from
   // ContentSuggestions.
   params.referrer =
-      web::Referrer(GURL(kNewTabPageReferrerURL), web::ReferrerPolicyDefault);
+      web::Referrer(GURL(ntp_snippets::GetContentSuggestionsReferrerURL()),
+                    web::ReferrerPolicyDefault);
   params.transition_type = ui::PAGE_TRANSITION_AUTO_BOOKMARK;
   [self.dispatcher loadURLWithParams:params];
   [self.NTPMetrics recordAction:new_tab_page_uma::ACTION_OPENED_SUGGESTION];