predictors: Add origin learning.

chrome/browser/predictors/resource_prefetch_common.h

 // 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.
 
 #ifndef CHROME_BROWSER_PREDICTORS_RESOURCE_PREFETCH_COMMON_H_
 #define CHROME_BROWSER_PREDICTORS_RESOURCE_PREFETCH_COMMON_H_
 
 #include <stddef.h>
 
 #include "base/feature_list.h"
@@ skipping 92 matching lines @@
   size_t max_urls_to_track;
   size_t max_hosts_to_track;
 
   // The number of times we should have seen a visit to this URL in history
   // to start tracking it. This is to ensure we don't bother with oneoff
   // entries. For hosts we track each one.
   size_t min_url_visit_count;
 
   // The maximum number of resources to store per entry.
   size_t max_resources_per_entry;
+  // The maximum number of origins to store per entry.
+  size_t max_origins_per_entry;
   // The number of consecutive misses after we stop tracking a resource URL.
   size_t max_consecutive_misses;
 
   // The minimum confidence (accuracy of hits) required for a resource to be
   // prefetched.
   float min_resource_confidence_to_trigger_prefetch;
   // The minimum number of times we must have a URL on record to prefetch it.
   size_t min_resource_hits_to_trigger_prefetch;
 
   // Maximum number of prefetches that can be inflight for a single navigation.
   size_t max_prefetches_inflight_per_navigation;
   // Maximum number of prefetches that can be inflight for a host for a single
   // navigation.
   size_t max_prefetches_inflight_per_host_per_navigation;
   // True iff the predictor could use a url-based database.
   bool is_url_learning_enabled;
+  // True iff the origin-based prediction is enabled.
+  bool is_origin_prediction_enabled;
 };
 
 }  // namespace predictors
 
 #endif  // CHROME_BROWSER_PREDICTORS_RESOURCE_PREFETCH_COMMON_H_