Limit the number of history urls indexed for omnibox suggestions.

components/omnibox/browser/omnibox_field_trial.cc

 // Copyright 2014 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 "components/omnibox/browser/omnibox_field_trial.h"
 
 #include <cmath>
 #include <string>
 
 #include "base/command_line.h"
 #include "base/feature_list.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/field_trial_params.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_split.h"
 #include "base/strings/string_util.h"
+#include "base/sys_info.h"
 #include "base/time/time.h"
 #include "build/build_config.h"
 #include "components/metrics/proto/omnibox_event.pb.h"
 #include "components/omnibox/browser/omnibox_switches.h"
 #include "components/omnibox/browser/url_index_private_data.h"
 #include "components/search/search.h"
 #include "components/variations/active_field_trials.h"
 #include "components/variations/metrics_util.h"
 #include "components/variations/variations_associated_data.h"
 
@@ skipping 410 matching lines @@
       kHQPExperimentalScoringTopicalityThresholdParam);
 
   double topicality_threshold;
   if (topicality_threshold_str.empty() ||
       !base::StringToDouble(topicality_threshold_str, &topicality_threshold))
     return 0.8f;
 
   return static_cast<float>(topicality_threshold);
 }
 
+int OmniboxFieldTrial::MaxNumHQPUrlsIndexedAtStartup() {
+  const char* param = kMaxNumHQPUrlsIndexedAtStartupOnNonLowEndDevicesParam;
+  if (base::SysInfo::IsLowEndDevice())
+    param = kMaxNumHQPUrlsIndexedAtStartupOnLowEndDevicesParam;
+  std::string param_value(variations::GetVariationParamValue(
+      kBundledExperimentFieldTrialName, param));
+  int num_urls;
+  if (base::StringToInt(param_value, &num_urls))
+    return num_urls;
+  // Default value is set to -1 for unlimited number of urls.
+  return -1;
+}
+
 bool OmniboxFieldTrial::HQPFixFewVisitsBug() {
   return variations::GetVariationParamValue(
       kBundledExperimentFieldTrialName,
       kHQPFixFewVisitsBugRule) == "true";
 }
 
 bool OmniboxFieldTrial::HQPFreqencyUsesSum() {
   return variations::GetVariationParamValue(kBundledExperimentFieldTrialName,
                                             kHQPFreqencyUsesSumRule) == "true";
 }
@@ skipping 257 matching lines @@
     "VisitedCountScoreBuckets";
 const char OmniboxFieldTrial::kHUPNewScoringVisitedCountUseDecayFactorParam[] =
     "VisitedCountUseDecayFactor";
 
 const char OmniboxFieldTrial::kHQPExperimentalScoringBucketsParam[] =
     "HQPExperimentalScoringBuckets";
 const char
     OmniboxFieldTrial::kHQPExperimentalScoringTopicalityThresholdParam[] =
       "HQPExperimentalScoringTopicalityThreshold";
 
+const char
+    OmniboxFieldTrial::kMaxNumHQPUrlsIndexedAtStartupOnLowEndDevicesParam[] =
+        "MaxNumHQPUrlsIndexedAtStartupOnLowEndDevices";
+const char
+    OmniboxFieldTrial::kMaxNumHQPUrlsIndexedAtStartupOnNonLowEndDevicesParam[] =
+        "MaxNumHQPUrlsIndexedAtStartupOnNonLowEndDevices";
+
 const char OmniboxFieldTrial::kPhysicalWebZeroSuggestBaseRelevanceParam[] =
     "PhysicalWebZeroSuggestBaseRelevance";
 const char OmniboxFieldTrial::kPhysicalWebAfterTypingBaseRelevanceParam[] =
     "PhysicalWebAfterTypingBaseRelevanceParam";
 
 const char OmniboxFieldTrial::kZeroSuggestRedirectToChromeServerAddressParam[] =
     "ZeroSuggestRedirectToChromeServerAddress";
 const char
     OmniboxFieldTrial::kZeroSuggestRedirectToChromeAdditionalFieldsParam[] =
         "ZeroSuggestRedirectToChromeAdditionalFields";
@@ skipping 56 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();
 }