Remove profile-based per-host & default zoom level migration code.

chrome/browser/prefs/browser_prefs.cc

 // Copyright 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/prefs/browser_prefs.h"
 
 #include <string>
 
 #include "base/metrics/histogram_macros.h"
 #include "base/prefs/pref_registry_simple.h"
@@ skipping 564 matching lines @@
   // TODO(bnc): https://crbug.com/401970  Remove migration code one year after
   // M38.
   chrome_browser_net::MigrateNetworkPredictionUserPrefs(profile_prefs);
 #endif
 
 #if defined(OS_CHROMEOS) && defined(ENABLE_APP_LIST)
   // Added 02/2015.
   MigrateGoogleNowPrefs(profile);
 #endif
 }
 

[gab, 2015/08/18 20:39:40]

https://codereview.chromium.org/541103002/diff/1040001/chrome/browser/prefs/b...
had introduced some includes, can they be cleaned here?

[wjmaclean, 2015/08/19 13:53:34]

Sorry, forgot about that.

-// As part of the migration from per-profile to per-partition HostZoomMaps,
-// we need to detect if an existing per-profile set of preferences exist, and
-// if so convert them to be per-partition. We migrate any per-profile zoom
-// level prefs via zoom_level_prefs.
-// Code that updates zoom prefs in the profile prefs store has been removed,
-// so once we clear these values here, they should never get set again.
-// TODO(wjmaclean): Remove this migration machinery after histograms show
-// that an aceptable percentage of users have been migrated.
-// crbug.com/420643
-void MigrateProfileZoomLevelPrefs(Profile* profile) {
-  PrefService* prefs = profile->GetPrefs();
-  chrome::ChromeZoomLevelPrefs* zoom_level_prefs = profile->GetZoomLevelPrefs();
-  DCHECK(zoom_level_prefs);
-
-  bool migrated = false;
-  // Only migrate the default zoom level if it is not equal to the registered
-  // default for the preference.
-  const base::Value* per_profile_default_zoom_level_value =
-      prefs->GetUserPrefValue(prefs::kDefaultZoomLevelDeprecated);
-  if (per_profile_default_zoom_level_value) {
-    if (per_profile_default_zoom_level_value->GetType() ==
-           base::Value::TYPE_DOUBLE) {
-      double per_profile_default_zoom_level = 0.0;
-      bool success = per_profile_default_zoom_level_value->GetAsDouble(
-          &per_profile_default_zoom_level);
-      DCHECK(success);
-      zoom_level_prefs->SetDefaultZoomLevelPref(per_profile_default_zoom_level);
-    }
-    prefs->ClearPref(prefs::kDefaultZoomLevelDeprecated);
-    migrated = true;
-  }
-
-  const base::DictionaryValue* host_zoom_dictionary =
-      prefs->GetDictionary(prefs::kPerHostZoomLevelsDeprecated);
-  // Collect stats on frequency with which migrations are occuring. This measure
-  // is not perfect, since it will consider an un-migrated user with only
-  // default value as being already migrated, but it will catch all non-trivial
-  // migrations.
-  migrated |= !host_zoom_dictionary->empty();
-  UMA_HISTOGRAM_BOOLEAN("Settings.ZoomLevelPreferencesMigrated", migrated);

[gab, 2015/08/18 20:39:40]

Also mark this histogram as obsolete.

[wjmaclean, 2015/08/19 13:53:34]

Done. I didn't realize that histograms had an 'obsolete' label ... good to know!

-
-  // Since |host_zoom_dictionary| is not partition-based, do not attempt to
-  // sanitize it.
-  zoom_level_prefs->ExtractPerHostZoomLevels(
-      host_zoom_dictionary, false /* sanitize_partition_host_zoom_levels */);
-
-  // We're done migrating the profile per-host zoom level values, so we clear
-  // them all.
-  DictionaryPrefUpdate host_zoom_dictionary_update(
-      prefs, prefs::kPerHostZoomLevelsDeprecated);
-  host_zoom_dictionary_update->Clear();
-}
-
 }  // namespace chrome