Don't demote top match for certain match types.

chrome/browser/autocomplete/autocomplete_result_unittest.cc

Index: chrome/browser/autocomplete/autocomplete_result_unittest.cc
diff --git a/chrome/browser/autocomplete/autocomplete_result_unittest.cc b/chrome/browser/autocomplete/autocomplete_result_unittest.cc
index babf1ae2cf5d4768004eeab36a37811a54eddd8e..839e4331fa6b05a6f9b0d2b7e58ca96c51cfa518 100644
--- a/chrome/browser/autocomplete/autocomplete_result_unittest.cc
+++ b/chrome/browser/autocomplete/autocomplete_result_unittest.cc
@@ -377,6 +377,67 @@ TEST_F(AutocompleteResultTest, SortAndCullWithDemotionsByType) {
             result.match_at(2)->destination_url.spec());
 }
 
+TEST_F(AutocompleteResultTest, SortAndCullWithUndemotableTypes) {
+  // Add some matches.
+  ACMatches matches;
+  {

[Peter Kasting, 2013/11/05 04:09:55]

Nit: Rather than these sub-blocks, you could simply create |matches| as a
3-element vector, then modify matches[0], matches[1], and matches[2].  This
would be both briefer and slightly more efficient (not that that matters...)

[H Fung, 2013/11/05 06:11:27]

Done.

+    AutocompleteMatch match;
+    match.destination_url = GURL("http://history-url/");
+    match.relevance = 1400;
+    match.allowed_to_be_default_match = true;
+    match.type = AutocompleteMatchType::HISTORY_URL;
+    matches.push_back(match);
+  }
+  {
+    AutocompleteMatch match;
+    match.destination_url = GURL("http://history-url2/");
+    match.relevance = 1300;
+    match.allowed_to_be_default_match = true;
+    match.type = AutocompleteMatchType::HISTORY_URL;
+    matches.push_back(match);
+  }
+  {
+    AutocompleteMatch match;
+    match.destination_url = GURL("http://search-what-you-typed/");
+    match.relevance = 1200;
+    match.allowed_to_be_default_match = true;
+    match.type = AutocompleteMatchType::SEARCH_WHAT_YOU_TYPED;
+    matches.push_back(match);
+  }
+
+  // Add a rule demoting history-url, but don't demote the top match.
+  {
+    std::map<std::string, std::string> params;
+    params[std::string(OmniboxFieldTrial::kDemoteByTypeRule) + ":3:*"] =
+        "1:50";  // 3 == HOME_PAGE

[Peter Kasting, 2013/11/05 04:09:55]

Nit: Since the '3' is not on the same physical line as the comment, this might
actually be better as a single comment above these two statements.  Or just
don't comment them -- if someone doesn't know what the "3" is, the ":" and ":*"
and "1:50" and such aren't going to be clear either.

[H Fung, 2013/11/05 06:11:27]

Done.  I kept the comment since HOME_PAGE is used below.

+    params[std::string(OmniboxFieldTrial::kUndemotableTopTypeRule) + ":3:*"] =
+        "1,5";  // 3 == HOME_PAGE
+    ASSERT_TRUE(chrome_variations::AssociateVariationParams(
+        OmniboxFieldTrial::kBundledExperimentFieldTrialName, "B", params));
+  }
+  base::FieldTrialList::CreateFieldTrial(
+      OmniboxFieldTrial::kBundledExperimentFieldTrialName, "B");
+
+  AutocompleteResult result;
+  result.AppendMatches(matches);
+  AutocompleteInput input(string16(), string16::npos, string16(), GURL(),
+                          AutocompleteInput::HOME_PAGE, false, false, false,
+                          AutocompleteInput::ALL_MATCHES);
+  result.SortAndCull(input, test_util_.profile());
+
+  // Check the new ordering.  The first history-url result should not be
+  // demoted, but the second result should be.
+  // We cannot check relevance scores because the matches are sorted by
+  // demoted relevance but the actual relevance scores are not modified.
+  ASSERT_EQ(3u, result.size());
+  EXPECT_EQ("http://history-url/",
+            result.match_at(0)->destination_url.spec());
+  EXPECT_EQ("http://search-what-you-typed/",
+            result.match_at(1)->destination_url.spec());
+  EXPECT_EQ("http://history-url2/",
+            result.match_at(2)->destination_url.spec());
+}
+
 TEST_F(AutocompleteResultTest, SortAndCullReorderForDefaultMatch) {
   TestData data[] = {
     { 0, 0, 1300 },