Log referrer chain length by verdict type

When Chrome gets password protection verdicts from Safe Browsing, we'd
like to log the referrer chain size by verdict type.

Bug: 864608
Change-Id: If11cd732c6c45865a64bfbbccf71af4615b148f9
Reviewed-on: https://chromium-review.googlesource.com/1141179
Commit-Queue: Jialiu Lin <jialiul@chromium.org>
Reviewed-by: Ilya Sherman <isherman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#576367}

components/safe_browsing/password_protection/password_protection_request.cc

@@ -48,6 +48,12 @@ const char kEnterprisePasswordEntryVerdictHistogram[] =
     "PasswordProtection.Verdict.NonGaiaEnterprisePasswordEntry";
 const char kGSuiteSyncPasswordEntryVerdictHistogram[] =
     "PasswordProtection.Verdict.GSuiteSyncPasswordEntry";
+const char kReferrerChainSizeOfSafeVerdictHistogram[] =
+    "PasswordProtection.ReferrerChainSize.Safe";
+const char kReferrerChainSizeOfPhishingVerdictHistogram[] =
+    "PasswordProtection.ReferrerChainSize.Phishing";
+const char kReferrerChainSizeOfLowRepVerdictHistogram[] =
+    "PasswordProtection.ReferrerChainSize.LowReputation";
 
 PasswordProtectionRequest::PasswordProtectionRequest(
     WebContents* web_contents,
@@ -403,6 +409,11 @@ void PasswordProtectionRequest::Finish(
       default:
         NOTREACHED();
     }
+    int referrer_chain_size =
+        request_proto_->frames_size() > 0
+            ? request_proto_->frames(0).referrer_chain_size()
+            : 0;
+    LogReferrerChainSize(response->verdict_type(), referrer_chain_size);
   }
 
   password_protection_service_->RequestFinished(
@@ -433,4 +444,26 @@ void PasswordProtectionRequest::HandleDeferredNavigations() {
   throttles_.clear();
 }
 
+void PasswordProtectionRequest::LogReferrerChainSize(
+    LoginReputationClientResponse::VerdictType verdict_type,
+    int referrer_chain_size) {
+  switch (verdict_type) {
+    case LoginReputationClientResponse::SAFE:
+      UMA_HISTOGRAM_COUNTS_100(kReferrerChainSizeOfSafeVerdictHistogram,
+                               referrer_chain_size);
+      return;
+    case LoginReputationClientResponse::LOW_REPUTATION:
+      UMA_HISTOGRAM_COUNTS_100(kReferrerChainSizeOfLowRepVerdictHistogram,
+                               referrer_chain_size);
+      return;
+    case LoginReputationClientResponse::PHISHING:
+      UMA_HISTOGRAM_COUNTS_100(kReferrerChainSizeOfPhishingVerdictHistogram,
+                               referrer_chain_size);
+      return;
+    case LoginReputationClientResponse::VERDICT_TYPE_UNSPECIFIED:
+      break;
+  }
+  NOTREACHED();
+}
+
 }  // namespace safe_browsing

components/safe_browsing/password_protection/password_protection_request.h

@@ -30,6 +30,9 @@ extern const char kSyncPasswordEntryVerdictHistogram[];
 extern const char kProtectedPasswordEntryVerdictHistogram[];
 extern const char kEnterprisePasswordEntryVerdictHistogram[];
 extern const char kGSuiteSyncPasswordEntryVerdictHistogram[];
+extern const char kReferrerChainSizeOfSafeVerdictHistogram[];
+extern const char kReferrerChainSizeOfPhishingVerdictHistogram[];
+extern const char kReferrerChainSizeOfLowRepVerdictHistogram[];
 
 // A request for checking if an unfamiliar login form or a password reuse event
 // is safe. PasswordProtectionRequest objects are owned by
@@ -151,6 +154,12 @@ class PasswordProtectionRequest
   void Finish(PasswordProtectionService::RequestOutcome outcome,
               std::unique_ptr<LoginReputationClientResponse> response);
 
+  // TODO(crbug.com/854314): Move this function to a separate util file.
+  // Logs the size of referrer chain by verdict type.
+  void LogReferrerChainSize(
+      LoginReputationClientResponse::VerdictType verdict_type,
+      int referrer_chain_size);
+
   // WebContents of the password protection event.
   content::WebContents* web_contents_;
 

components/safe_browsing/password_protection/password_protection_service_unittest.cc

@@ -739,6 +739,7 @@ TEST_P(PasswordProtectionServiceTest,
       ElementsAre(base::Bucket(1 /* SUCCEEDED */, 1)));
   EXPECT_THAT(histograms_.GetAllSamples(kPasswordOnFocusVerdictHistogram),
               ElementsAre(base::Bucket(3 /* PHISHING */, 1)));
+  histograms_.ExpectTotalCount(kReferrerChainSizeOfPhishingVerdictHistogram, 1);
   LoginReputationClientResponse* actual_response =
       password_protection_service_->latest_response();
   EXPECT_EQ(expected_response.verdict_type(), actual_response->verdict_type());
@@ -786,6 +787,7 @@ TEST_P(PasswordProtectionServiceTest,
   EXPECT_THAT(
       histograms_.GetAllSamples(kProtectedPasswordEntryVerdictHistogram),
       ElementsAre(base::Bucket(3 /* PHISHING */, 1)));
+  histograms_.ExpectTotalCount(kReferrerChainSizeOfPhishingVerdictHistogram, 1);
 }
 
 TEST_P(PasswordProtectionServiceTest,
@@ -823,6 +825,7 @@ TEST_P(PasswordProtectionServiceTest,
   EXPECT_THAT(histograms_.GetAllSamples(kSyncPasswordEntryVerdictHistogram),
               ElementsAre(base::Bucket(3 /* PHISHING */, 1)));
   histograms_.ExpectTotalCount(kProtectedPasswordEntryVerdictHistogram, 0);
+  histograms_.ExpectTotalCount(kReferrerChainSizeOfPhishingVerdictHistogram, 1);
 }
 
 TEST_P(PasswordProtectionServiceTest, TestTearDownWithPendingRequests) {

tools/metrics/histograms/histograms.xml

@@ -70152,6 +70152,16 @@ uploading your change for review.
   </summary>
 </histogram>
 
+<histogram name="PasswordProtection.ReferrerChainSize" units="referrers"
+    expires_after="M71">
+  <owner>drubery@chromium.org</owner>
+  <owner>jialiul@chromium.org</owner>
+  <summary>
+    The referrer chain size of a password protection request. This is recorded
+    when Chrome receives a verdict for this request.
+  </summary>
+</histogram>
+
 <histogram name="PasswordProtection.RequestNetworkDuration" units="ms">
   <owner>jialiul@chromium.org</owner>
   <owner>nparker@chromium.org</owner>
@@ -123284,6 +123294,15 @@ uploading your change for review.
   <affected-histogram name="PasswordProtection.Verdict"/>
 </histogram_suffixes>
 
+<histogram_suffixes name="PasswordProtectionVerdict" separator=".">
+  <suffix name="LowReputation"
+      label="Password protection reponse with low reputation verdict"/>
+  <suffix name="Phishing"
+      label="Password protection response with phishing verdict"/>
+  <suffix name="Safe" label="Password protection response with safe verdict"/>
+  <affected-histogram name="PasswordProtection.ReferrerChainSize"/>
+</histogram_suffixes>
+
 <histogram_suffixes name="PasswordReuseSourceRealm" separator=".">
   <suffix name="FromHttpRealm"
       label="The account in question was saved on an HTTP site."/>