Increase the NQE cache size from 3 to 10

net/nqe/network_qualities_prefs_manager.cc

 // Copyright 2016 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 "net/nqe/network_qualities_prefs_manager.h"
 
 #include <string>
 #include <utility>
 
 #include "base/bind.h"
 #include "base/rand_util.h"
 #include "base/sequenced_task_runner.h"
 #include "base/threading/thread_checker.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "net/nqe/network_quality_estimator.h"
 
 namespace net {
 
 namespace {
 
 // Maximum size of the prefs that hold the qualities of different networks.
-static const size_t kMaxCacheSize = 3u;
+// A single entry in the cache consists of three tuples:
+// (i)   SSID or MCCMNC of the network. SSID is at most 32 characters in length
+//       (but is typically shorter than that). MCCMNC is at most 6 characters
+//       long.
+// (ii)  Connection type of the network as reported by network
+//       change notifier (an enum).
+// (iii) Effective connection type of the network (an enum).
+static const size_t kMaxCacheSize = 10u;
 
 // Parses |value| into a map of NetworkIDs and CachedNetworkQualities,
 // and returns the map.
 ParsedPrefs ConvertDictionaryValueToMap(const base::DictionaryValue* value) {
   ParsedPrefs read_prefs;
 
   DCHECK_GE(kMaxCacheSize, value->size());
 
   for (base::DictionaryValue::Iterator it(*value); !it.IsAtEnd();
        it.Advance()) {
@@ skipping 130 matching lines @@
 }
 
 ParsedPrefs NetworkQualitiesPrefsManager::ForceReadPrefsForTesting() const {
   DCHECK(pref_task_runner_->RunsTasksOnCurrentThread());
   std::unique_ptr<base::DictionaryValue> value(
       pref_delegate_->GetDictionaryValue());
   return ConvertDictionaryValueToMap(value.get());
 }
 
 }  // namespace net