Extend referrer chain for SBER users to 5 gestures

Based on some example campaigns for which chrome sync history won't be
useful, extend the maximum number of gestures in a referrer chain to
5 gestures. We can then evaluate how useful the extra data is, and
possible extend the maximum gestures for all users.

Bug: 864266
Change-Id: Idbcc2e07f7593a90f05ba07a2e1ef0c2a1be757b
Reviewed-on: https://chromium-review.googlesource.com/c/1287041
Commit-Queue: Daniel Rubery <drubery@chromium.org>
Reviewed-by: Jialiu Lin <jialiul@chromium.org>
Reviewed-by: Varun Khaneja <vakh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#600883}

chrome/browser/safe_browsing/download_protection/download_protection_service.cc

@@ -44,6 +44,7 @@ const double kWhitelistDownloadSampleRate = 0.01;
 
 // The number of user gestures we trace back for download attribution.
 const int kDownloadAttributionUserGestureLimit = 2;
+const int kDownloadAttributionUserGestureLimitForExtendedReporting = 5;
 
 void AddEventUrlToReferrerChain(const download::DownloadItem& item,
                                 ReferrerChain* out_referrer_chain) {
@@ -74,6 +75,26 @@ bool MatchesEnterpriseWhitelist(const Profile* profile,
   return false;
 }
 
+int GetDownloadAttributionUserGestureLimit(const download::DownloadItem& item) {
+  content::WebContents* web_contents =
+      content::DownloadItemUtils::GetWebContents(
+          const_cast<download::DownloadItem*>(&item));
+  if (!web_contents)
+    return kDownloadAttributionUserGestureLimit;
+
+  Profile* profile =
+      Profile::FromBrowserContext(web_contents->GetBrowserContext());
+  if (!profile)
+    return kDownloadAttributionUserGestureLimit;
+
+  const PrefService* prefs = profile->GetPrefs();
+  if (!prefs)
+    return kDownloadAttributionUserGestureLimit;
+  if (!IsExtendedReportingEnabled(*prefs))
+    return kDownloadAttributionUserGestureLimit;
+  return kDownloadAttributionUserGestureLimitForExtendedReporting;
+}
+
 }  // namespace
 
 const void* const DownloadProtectionService::kDownloadPingTokenKey =
@@ -426,8 +447,8 @@ DownloadProtectionService::IdentifyReferrerChain(
   // We look for the referrer chain that leads to the download url first.
   SafeBrowsingNavigationObserverManager::AttributionResult result =
       navigation_observer_manager_->IdentifyReferrerChainByEventURL(
-          item.GetURL(), download_tab_id, kDownloadAttributionUserGestureLimit,
-          referrer_chain.get());
+          item.GetURL(), download_tab_id,
+          GetDownloadAttributionUserGestureLimit(item), referrer_chain.get());
 
   // If no navigation event is found, this download is not triggered by regular
   // navigation (e.g. html5 file apis, etc). We look for the referrer chain
@@ -437,7 +458,7 @@ DownloadProtectionService::IdentifyReferrerChain(
       web_contents && web_contents->GetLastCommittedURL().is_valid()) {
     AddEventUrlToReferrerChain(item, referrer_chain.get());
     result = navigation_observer_manager_->IdentifyReferrerChainByWebContents(
-        web_contents, kDownloadAttributionUserGestureLimit,
+        web_contents, GetDownloadAttributionUserGestureLimit(item),
         referrer_chain.get());
   }
 

chrome/browser/safe_browsing/download_protection/download_protection_service.h

@@ -194,12 +194,14 @@ class DownloadProtectionService {
                            PPAPIDownloadRequest_InvalidResponse);
   FRIEND_TEST_ALL_PREFIXES(DownloadProtectionServiceTest,
                            PPAPIDownloadRequest_Timeout);
-  FRIEND_TEST_ALL_PREFIXES(DownloadProtectionServiceTest,
-                           VerifyReferrerChainWithEmptyNavigationHistory);
   FRIEND_TEST_ALL_PREFIXES(DownloadProtectionServiceFlagTest,
                            CheckClientDownloadOverridenByFlag);
   FRIEND_TEST_ALL_PREFIXES(DownloadProtectionServiceTest,
                            VerifyMaybeSendDangerousDownloadOpenedReport);
+  FRIEND_TEST_ALL_PREFIXES(DownloadProtectionServiceTest,
+                           VerifyReferrerChainWithEmptyNavigationHistory);
+  FRIEND_TEST_ALL_PREFIXES(DownloadProtectionServiceTest,
+                           VerifyReferrerChainLengthForExtendedReporting);
 
   static const void* const kDownloadPingTokenKey;
 

chrome/browser/safe_browsing/safe_browsing_navigation_observer_manager.cc

@@ -49,7 +49,7 @@ bool IsEventExpired(const base::Time& event_time, double ttl_in_second) {
 // Helper function to determine if the URL type should be LANDING_REFERRER or
 // LANDING_PAGE, and modify AttributionResult accordingly.
 ReferrerChainEntry::URLType GetURLTypeAndAdjustAttributionResult(
-    bool at_user_gesture_limit,
+    size_t user_gesture_count,
     SafeBrowsingNavigationObserverManager::AttributionResult* out_result) {
   // Landing page refers to the page user directly interacts with to trigger
   // this event (e.g. clicking on download button). Landing referrer page is the
@@ -57,13 +57,19 @@ ReferrerChainEntry::URLType GetURLTypeAndAdjustAttributionResult(
   // Since we are tracing navigations backwards, if we've reached
   // user gesture limit before this navigation event, this is a navigation
   // leading to the landing referrer page, otherwise it leads to landing page.
-  if (at_user_gesture_limit) {
+  if (user_gesture_count == 0) {
+    *out_result = SafeBrowsingNavigationObserverManager::SUCCESS;
+    return ReferrerChainEntry::EVENT_URL;
+  } else if (user_gesture_count == 2) {
     *out_result =
         SafeBrowsingNavigationObserverManager::SUCCESS_LANDING_REFERRER;
     return ReferrerChainEntry::LANDING_REFERRER;
-  } else {
+  } else if (user_gesture_count == 1) {
     *out_result = SafeBrowsingNavigationObserverManager::SUCCESS_LANDING_PAGE;
     return ReferrerChainEntry::LANDING_PAGE;
+  } else {
+    *out_result = SafeBrowsingNavigationObserverManager::SUCCESS_REFERRER;
+    return ReferrerChainEntry::REFERRER;
   }
 }
 
@@ -424,8 +430,7 @@ SafeBrowsingNavigationObserverManager::IdentifyReferrerChainByHostingPage(
     user_gesture_count = 1;
     AddToReferrerChain(
         out_referrer_chain, nav_event, initiating_main_frame_url,
-        GetURLTypeAndAdjustAttributionResult(
-            user_gesture_count == user_gesture_count_limit, &result));
+        GetURLTypeAndAdjustAttributionResult(user_gesture_count, &result));
   } else {
     AddToReferrerChain(out_referrer_chain, nav_event, initiating_main_frame_url,
                        ReferrerChainEntry::CLIENT_REDIRECT);
@@ -667,11 +672,10 @@ void SafeBrowsingNavigationObserverManager::GetRemainingReferrerChain(
     if (!last_nav_event_traced)
       return;
 
-    AddToReferrerChain(
-        out_referrer_chain, last_nav_event_traced, last_main_frame_url_traced,
-        GetURLTypeAndAdjustAttributionResult(
-            current_user_gesture_count == user_gesture_count_limit,
-            out_result));
+    AddToReferrerChain(out_referrer_chain, last_nav_event_traced,
+                       last_main_frame_url_traced,
+                       GetURLTypeAndAdjustAttributionResult(
+                           current_user_gesture_count, out_result));
     // Stop searching if the size of out_referrer_chain already reached its
     // limit.
     if (out_referrer_chain->size() == kReferrerChainMaxLength)

components/safe_browsing/browser/referrer_chain_provider.h

@@ -26,6 +26,8 @@ class ReferrerChainProvider {
     SUCCESS_LANDING_REFERRER = 3,  // Successfully identified landing referrer.
     INVALID_URL = 4,
     NAVIGATION_EVENT_NOT_FOUND = 5,
+    SUCCESS_REFERRER = 6,  // Successfully identified extra referrers beyond the
+                           // landing referrer.
 
     // Always at the end.
     ATTRIBUTION_FAILURE_TYPE_MAX

components/safe_browsing/proto/csd.proto

@@ -660,6 +660,11 @@ message ReferrerChainEntry {
     // chain is empty or partially missing, we will add/append recent navigation
     // events to this list. RECENT_NAVIGATION type is set for these cases.
     RECENT_NAVIGATION = 6;
+
+    // The REFERRER type is used for entries that recede the LANDING_REFERRER in
+    // the referrer chain, when more than two gestures are included in the
+    // referrer chain.
+    REFERRER = 7;
   }
 
   enum NavigationInitiation {

components/safe_browsing/web_ui/safe_browsing_ui.cc

@@ -376,6 +376,9 @@ base::Value SerializeReferrer(const ReferrerChainEntry& referrer) {
     case ReferrerChainEntry::RECENT_NAVIGATION:
       url_type = "RECENT_NAVIGATION";
       break;
+    case ReferrerChainEntry::REFERRER:
+      url_type = "REFERRER";
+      break;
   }
   referrer_dict.SetKey("type", base::Value(url_type));