Migrate HostReferralList and StartupDNSPrefetchList from local_state to user ...

chrome/browser/net/predictor_api.cc

 // Copyright (c) 2010 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/net/predictor_api.h"
 
 #include <map>
 #include <string>
 
 #include "base/metrics/field_trial.h"
@@ skipping 115 matching lines @@
 
 void OnTheRecord(bool enable) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   if (on_the_record_switch == enable)
     return;
   on_the_record_switch = enable;
   if (on_the_record_switch)
     g_browser_process->io_thread()->ChangedToOnTheRecord();
 }
 
-void RegisterPrefs(PrefService* local_state) {
-  local_state->RegisterListPref(prefs::kDnsStartupPrefetchList);
-  local_state->RegisterListPref(prefs::kDnsHostReferralList);
-}
-
 void RegisterUserPrefs(PrefService* user_prefs) {
+  user_prefs->RegisterListPref(prefs::kDnsStartupPrefetchList);
+  user_prefs->RegisterListPref(prefs::kDnsHostReferralList);
   user_prefs->RegisterBooleanPref(prefs::kDnsPrefetchingEnabled, true);
 }
 
 // When enabled, we use the following instance to service all requests in the
 // browser process.
 // TODO(willchan): Look at killing this.
 static Predictor* g_predictor = NULL;
 
 // This API is only used in the browser process.
 // It is called from an IPC message originating in the renderer.  It currently
@@ skipping 233 matching lines @@
                                  bool preconnect_enabled) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
   bool prefetching_enabled =
       user_prefs->GetBoolean(prefs::kDnsPrefetchingEnabled);
 
   // Gather the list of hostnames to prefetch on startup.
   UrlList urls =
       GetPredictedUrlListAtStartup(user_prefs, local_state);
 
+  // Migrate HostReferralList from local_state to user prefs if needed.
   ListValue* referral_list =
-      static_cast<ListValue*>(
-          local_state->GetMutableList(prefs::kDnsHostReferralList)->DeepCopy());
+      (local_state->FindPreference(prefs::kDnsHostReferralList)) ?

[jar (doing other things), 2010/12/13 20:27:29]

If this is where you migrate the data, perhaps it should be where you delete old
data (and not just copy it).

...thinking about this some more... 

This data is all "learned data" used for optimizing connections (and startup). 
It would not be  the worst thing if you simply discarded old data (i.e.,
critical stuff would be relearned quickly enough).

The critical point IMO is the discard of old data, both for efficiency, and for
security.  I'm not a profiles expert, so that is the detail I'm most curious
about.

[Miranda Callahan, 2010/12/14 01:03:49]

I think everything you say about deleting old data makes great sense.  Changed
the code to reflect this idea.

+    static_cast<ListValue*>(
+        local_state->GetMutableList(prefs::kDnsHostReferralList)->DeepCopy()) :
+    static_cast<ListValue*>(
+        user_prefs->GetMutableList(prefs::kDnsHostReferralList)->DeepCopy());
 
   g_browser_process->io_thread()->InitNetworkPredictor(
       prefetching_enabled, max_dns_queue_delay, max_parallel_resolves, urls,
       referral_list, preconnect_enabled);
 }
 
 void FinalizePredictorInitialization(
     Predictor* global_predictor,
     const UrlList& startup_urls,
     ListValue* referral_list) {
@@ skipping 64 matching lines @@
 }
 
 static UrlList GetPredictedUrlListAtStartup(PrefService* user_prefs,
                                             PrefService* local_state) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   UrlList urls;
   // Recall list of URLs we learned about during last session.
   // This may catch secondary hostnames, pulled in by the homepages.  It will
   // also catch more of the "primary" home pages, since that was (presumably)
   // rendered first (and will be rendered first this time too).
+  // Migrate StartupPrefetchList from local_state to user prefs if needed.
   ListValue* startup_list =
-      local_state->GetMutableList(prefs::kDnsStartupPrefetchList);
+      (local_state->FindPreference(prefs::kDnsStartupPrefetchList)) ?
+    local_state->GetMutableList(prefs::kDnsStartupPrefetchList) :
+    user_prefs->GetMutableList(prefs::kDnsStartupPrefetchList);
+
   if (startup_list) {
     ListValue::iterator it = startup_list->begin();
     int format_version = -1;
     if (it != startup_list->end() &&
         (*it)->GetAsInteger(&format_version) &&
         format_version == kPredictorStartupFormatVersion) {
       ++it;
       for (; it != startup_list->end(); ++it) {
         std::string url_spec;
         if (!(*it)->GetAsString(&url_spec)) {
@@ skipping 120 matching lines @@
     DCHECK(!g_predictor);
     InitNetworkPredictor(max_queueing_delay, max_parallel_resolves, user_prefs,
                          local_state, preconnect_enabled);
   }
 }
 
 PredictorInit::~PredictorInit() {
 }
 
 }  // namespace chrome_browser_net