Omnibox: Launch URL Demotion in the Fakebox by Default

chrome/browser/omnibox/omnibox_field_trial.cc

 // Copyright (c) 2012 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 "chrome/browser/omnibox/omnibox_field_trial.h"
 
 #include <cmath>
 #include <string>
 
 #include "base/metrics/field_trial.h"
@@ skipping 304 matching lines @@
 bool OmniboxFieldTrial::SearchHistoryDisable(
     AutocompleteInput::PageClassification current_page_classification) {
   return OmniboxFieldTrial::GetValueForRuleInContext(
       kSearchHistoryRule, current_page_classification) == "Disable";
 }
 
 void OmniboxFieldTrial::GetDemotionsByType(
     AutocompleteInput::PageClassification current_page_classification,
     DemotionMultipliers* demotions_by_type) {
   demotions_by_type->clear();
-  const std::string demotion_rule =
-      OmniboxFieldTrial::GetValueForRuleInContext(
-          kDemoteByTypeRule,
-          current_page_classification);
+  std::string demotion_rule = OmniboxFieldTrial::GetValueForRuleInContext(
+      kDemoteByTypeRule, current_page_classification);
+  // If there is no demotion rule for this context, then use the default
+  // value for that context.  At the moment the default value is non-empty
+  // only for the fakebox-focus context.
+  if (demotion_rule.empty() &&
+      (current_page_classification ==
+       AutocompleteInput::INSTANT_NTP_WITH_FAKEBOX_AS_STARTING_FOCUS))
+    demotion_rule = "1:61,2:61,3:61,4:61,12:61";
+
   // The value of the DemoteByType rule is a comma-separated list of
   // {ResultType + ":" + Number} where ResultType is an AutocompleteMatchType::
   // Type enum represented as an integer and Number is an integer number
   // between 0 and 100 inclusive.   Relevance scores of matches of that result
   // type are multiplied by Number / 100.  100 means no change.
   base::StringPairs kv_pairs;
   if (base::SplitStringIntoKeyValuePairs(demotion_rule, ':', ',', &kv_pairs)) {
     for (base::StringPairs::const_iterator it = kv_pairs.begin();
          it != kv_pairs.end(); ++it) {
       // This is a best-effort conversion; we trust the hand-crafted parameters
@@ skipping 190 matching lines @@
   if (it != params.end())
     return it->second;
   // Fall back to the global instant extended context.
   it = params.find(rule + ":" + page_classification_str + ":*");
   if (it != params.end())
     return it->second;
   // Look up rule in the global context.
   it = params.find(rule + ":*:*");
   return (it != params.end()) ? it->second : std::string();
 }