Remove the migration code from content_settings::DefaultProvider.

components/content_settings/core/common/pref_names.cc

Index: components/content_settings/core/common/pref_names.cc
diff --git a/components/content_settings/core/common/pref_names.cc b/components/content_settings/core/common/pref_names.cc
index 4e78675bdac885f827de5fa763f1a37090c500e1..0dd75a668ab24489f32d24e8211c5e5814d4d58d 100644
--- a/components/content_settings/core/common/pref_names.cc
+++ b/components/content_settings/core/common/pref_names.cc
@@ -24,15 +24,6 @@ const char kContentSettingsPatternPairs[] =
 const char kContentSettingsWindowLastTabIndex[] =
     "content_settings_window.last_tab_index";
 
-// Dictionary of content settings applied to all hosts by default.
-// TODO(msramek): Deprecated. Use the individual preferences below.
-const char kDefaultContentSettings[] = "profile.default_content_settings";
-
-// Whether |kDefaultContentSettings| has already been migrated to
-// |kDefault<type>Setting| prefs.
-const char kMigratedDefaultContentSettings[] =
-    "profile.migrated_default_content_settings";

[battre, 2015/07/27 08:32:36]

I think there is traditionally one more step:

Move this out of the public .../pref_names.{cc,h} files into
content_settings_default_provider.cc as kObsolete...; then add a function
DiscardObsoletePreferences that is called from
DefaultProvider::RegisterProfilePrefs and deletes the entries from the
preferences file so that it does not collect unused junk over time.

[msramek, 2015/07/27 09:13:27]

Done. But it cannot be called from static RegisterProfilePrefs, as it refers to
non-static member PrefService.

-
 // Preferences storing the default values for individual content settings.
 const char kDefaultCookiesSetting[] =
     "profile.default_content_setting_values.cookies";