[Simplified domains] Add feature parameter for keyword heuristic.

This CL just adds a feature parameter to tune whether or not to use the keyword
heuristic for eTLD+1 elision. The param defaults to true so that
manually-opted-in users get the full elision behavior.

Fixed: 1122309
Change-Id: I334305d9ada6044dadbdf39d283253aae51d26f9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2378739Reviewed-by: Emily Stark <estark@chromium.org>
Commit-Queue: Joe DeBlasio <jdeblasio@chromium.org>
Cr-Commit-Position: refs/heads/master@{#802058}

chrome/browser/reputation/url_elision_policy.cc

@@ -18,6 +18,8 @@ namespace {
 
 const base::FeatureParam<int> kMaximumUnelidedHostnameLength{
     &omnibox::kMaybeElideToRegistrableDomain, "max_unelided_host_length", 25};
+const base::FeatureParam<bool> kEnableKeywordBasedElision{
+    &omnibox::kMaybeElideToRegistrableDomain, "enable_keyword_elision", true};
 
 }  // namespace
 
@@ -42,7 +44,8 @@ bool ShouldElideToRegistrableDomain(const GURL& url) {
   // Hostnames using sensitive keywords (typically, brandnames) are often social
   // engineering, and thus should only show the registrable domain.
   auto eTLD_plus_one = GetETLDPlusOne(host);
-  if (HostnameContainsKeyword(url, eTLD_plus_one, top500_domains::kTopKeywords,
+  if (kEnableKeywordBasedElision.Get() &&
+      HostnameContainsKeyword(url, eTLD_plus_one, top500_domains::kTopKeywords,
                               top500_domains::kNumTopKeywords)) {
     return true;
   }

chrome/browser/reputation/url_elision_policy_unittest.cc

@@ -15,14 +15,20 @@ namespace test {
 #include "components/url_formatter/spoof_checks/common_words/common_words_test-inc.cc"
 }
 
+namespace {
+
+// Note: This number is arbitrary; we just need to be able to build
+// hostnames that are reliably shorter/longer than the limit.
+const char* kMaxUnelidedHostLengthParam = "20";
+
+}  // namespace
+
 class UrlElisionPolicyTest : public testing::Test {
  public:
   UrlElisionPolicyTest() {
     scoped_feature_list_.InitWithFeaturesAndParameters(
         {{omnibox::kMaybeElideToRegistrableDomain,
-          // Note: This number is arbitrary; we just need to be able to build
-          // hostnames that are reliably shorter/longer than the limit.
-          {{"max_unelided_host_length", "20"}}}},
+          {{"max_unelided_host_length", kMaxUnelidedHostLengthParam}}}},
         {});
     url_formatter::common_words::SetCommonWordDAFSAForTesting(
         test::kDafsa, sizeof(test::kDafsa));
@@ -98,3 +104,39 @@ TEST_F(UrlElisionPolicyTest, ElidesKeywordedDomainsAppropriately) {
   EXPECT_FALSE(
       ShouldElideToRegistrableDomain(GURL("ftp://google.login.com/xyz")));
 }
+
+class UrlElisionKeywordPolicyTest : public UrlElisionPolicyTest,
+                                    public testing::WithParamInterface<bool> {
+ public:
+  UrlElisionKeywordPolicyTest() {
+    if (!GetParam()) {
+      scoped_feature_list_.InitWithFeaturesAndParameters(
+          {{omnibox::kMaybeElideToRegistrableDomain,
+            {{"max_unelided_host_length", kMaxUnelidedHostLengthParam}}}},
+          {});
+    } else {
+      scoped_feature_list_.InitWithFeaturesAndParameters(
+          {{omnibox::kMaybeElideToRegistrableDomain,
+            {{"max_unelided_host_length", kMaxUnelidedHostLengthParam},
+             {"enable_keyword_elision", "false"}}}},
+          {});
+    }
+  }
+
+  ~UrlElisionKeywordPolicyTest() override = default;
+
+  bool IsKeywordElisionEnabled() { return !GetParam(); }
+
+ private:
+  base::test::ScopedFeatureList scoped_feature_list_;
+
+  DISALLOW_COPY_AND_ASSIGN(UrlElisionKeywordPolicyTest);
+};
+
+INSTANTIATE_TEST_SUITE_P(All, UrlElisionKeywordPolicyTest, testing::Bool());
+
+// Verify that keyword elision follows the feature parameter.
+TEST_P(UrlElisionKeywordPolicyTest, ElidesOnKeywords) {
+  EXPECT_EQ(IsKeywordElisionEnabled(),
+            ShouldElideToRegistrableDomain(GURL("http://google-evil.com/xyz")));
+}