Remove the migration code from content_settings::PrefProvider.

components/content_settings/core/browser/content_settings_pref.cc

Index: components/content_settings/core/browser/content_settings_pref.cc
diff --git a/components/content_settings/core/browser/content_settings_pref.cc b/components/content_settings/core/browser/content_settings_pref.cc
index a519cef89b0abf0522508821f936555d1970be3f..535bcc6530a15f5a1dc32d066a988be866936e50 100644
--- a/components/content_settings/core/browser/content_settings_pref.cc
+++ b/components/content_settings/core/browser/content_settings_pref.cc
@@ -23,7 +23,6 @@ namespace {
 
 const char kSettingPath[] = "setting";
 const char kPerResourceIdentifierPrefName[] = "per_resource";
-const char kPerPluginPrefName[] = "per_plugin";
 const char kLastUsed[] = "last_used";
 
 ContentSetting FixObsoleteCookiePromptMode(ContentSettingsType content_type,
@@ -53,7 +52,6 @@ ContentSettingsPref::ContentSettingsPref(
     PrefChangeRegistrar* registrar,
     const char* pref_name,
     bool incognito,
-    bool* updating_old_preferences_flag,
     NotifyObserversCallback notify_callback)
     : content_type_(content_type),
       prefs_(prefs),
@@ -61,23 +59,10 @@ ContentSettingsPref::ContentSettingsPref(
       pref_name_(pref_name),
       is_incognito_(incognito),
       updating_preferences_(false),
-      updating_old_preferences_(updating_old_preferences_flag),
       notify_callback_(notify_callback) {
   DCHECK(prefs_);
 
-  // If the migration hasn't happened yet, or if this content setting
-  // is syncable, the parent |PrefProvider| is going to copy the contents
-  // of the old preference to this new preference. There is no need
-  // to initialize this preference separately (in fact, in the case
-  // of migration, we would be writing the empty new preference back to the
-  // old one, erasing it). Since copying between preferences is disallowed
-  // in incognito, |ContentSettingsPref| needs to be initialized from the new
-  // preference in incognito as well.
-  if ((prefs_->GetBoolean(prefs::kMigratedContentSettingsPatternPairs) &&
-       !IsContentSettingsTypeSyncable(content_type_))
-      || is_incognito_) {
-    ReadContentSettingsFromPrefAndWriteToOldPref();
-  }
+  ReadContentSettingsFromPref();
 
   registrar_->Add(
       pref_name_,
@@ -139,12 +124,6 @@ bool ContentSettingsPref::SetWebsiteSetting(
                secondary_pattern,
                resource_identifier,
                value.get());
-    if (IsContentSettingsTypeSyncable(content_type_)) {
-      UpdateOldPref(primary_pattern,
-                    secondary_pattern,
-                    resource_identifier,
-                    value.get());
-    }
   }
 
   notify_callback_.Run(
@@ -167,16 +146,13 @@ void ContentSettingsPref::ClearAllContentSettingsRules() {
   }
 
   if (!is_incognito_) {
-    // Clear the new preference.
+    // Clear the preference.
     {
       base::AutoReset<bool> auto_reset(&updating_preferences_, true);
       DictionaryPrefUpdate update(prefs_, pref_name_);
       base::DictionaryValue* pattern_pairs_settings = update.Get();
       pattern_pairs_settings->Clear();
     }
-
-    if (IsContentSettingsTypeSyncable(content_type_))
-      ClearOldPreference();
   }
 
   notify_callback_.Run(ContentSettingsPattern(),
@@ -249,14 +225,14 @@ size_t ContentSettingsPref::GetNumExceptions() {
   return value_map_.size();
 }
 
-void ContentSettingsPref::ReadContentSettingsFromPrefAndWriteToOldPref() {
-  // Clear the old preference, so we can copy the exceptions from the new
-  // preference into it. Note that copying in this direction is disallowed
-  // in incognito, to avoid the echo effect: New preference -> PrefProvider ->
-  // Old preference -> Incognito PrefProvider -> New preference -> etc.
-  if (!is_incognito_ && IsContentSettingsTypeSyncable(content_type_))
-    ClearOldPreference();
+bool ContentSettingsPref::TryLockForTesting() const {
+  if (!lock_.Try())
+    return false;
+  lock_.Release();
+  return true;
+}
 
+void ContentSettingsPref::ReadContentSettingsFromPref() {
   // |DictionaryPrefUpdate| sends out notifications when destructed. This
   // construction order ensures |AutoLock| gets destroyed first and |lock_| is
   // not held when the notifications are sent. Also, |auto_reset| must be still
@@ -328,12 +304,6 @@ void ContentSettingsPref::ReadContentSettingsFromPrefAndWriteToOldPref() {
                               content_type_,
                               resource_identifier,
                               setting_ptr->DeepCopy());
-          if (!is_incognito_ && IsContentSettingsTypeSyncable(content_type_)) {
-              UpdateOldPref(pattern_pair.first,
-                            pattern_pair.second,
-                            resource_identifier,
-                            setting_ptr.get());
-          }
         }
       }
     }
@@ -364,12 +334,6 @@ void ContentSettingsPref::ReadContentSettingsFromPrefAndWriteToOldPref() {
                           content_type_,
                           ResourceIdentifier(),
                           value->DeepCopy());
-      if (!is_incognito_ && IsContentSettingsTypeSyncable(content_type_)) {
-          UpdateOldPref(pattern_pair.first,
-                        pattern_pair.second,
-                        ResourceIdentifier(),
-                        value_ptr.get());
-      }
       if (content_type_ == CONTENT_SETTINGS_TYPE_COOKIES) {
         ContentSetting s = ValueToContentSetting(value);
         switch (s) {
@@ -407,7 +371,7 @@ void ContentSettingsPref::OnPrefChanged() {
   if (updating_preferences_)
     return;
 
-  ReadContentSettingsFromPrefAndWriteToOldPref();
+  ReadContentSettingsFromPref();
 
   notify_callback_.Run(ContentSettingsPattern(),
                        ContentSettingsPattern(),
@@ -486,127 +450,6 @@ void ContentSettingsPref::UpdatePref(
   }
 }
 
-void ContentSettingsPref::UpdateOldPref(
-    const ContentSettingsPattern& primary_pattern,
-    const ContentSettingsPattern& secondary_pattern,
-    const ResourceIdentifier& resource_identifier,
-    const base::Value* value) {
-  DCHECK(IsContentSettingsTypeSyncable(content_type_));
-
-  // The incognito provider cannot write the settings to avoid echo effect:
-  // New preference -> PrefProvider -> Old preference ->
-  // -> Incognito PrefProvider -> New preference -> etc.
-  DCHECK(!is_incognito_);
-
-  if (*updating_old_preferences_)
-    return;
-
-  base::AutoReset<bool> auto_reset(updating_old_preferences_, true);
-  {
-    DictionaryPrefUpdate update(prefs_,
-                                prefs::kContentSettingsPatternPairs);
-    base::DictionaryValue* pattern_pairs_settings = update.Get();
-
-    // Get settings dictionary for the given patterns.
-    std::string pattern_str(CreatePatternString(primary_pattern,
-                                                secondary_pattern));
-    base::DictionaryValue* settings_dictionary = NULL;
-    bool found = pattern_pairs_settings->GetDictionaryWithoutPathExpansion(
-        pattern_str, &settings_dictionary);
-
-    if (!found && value) {
-      settings_dictionary = new base::DictionaryValue;
-      pattern_pairs_settings->SetWithoutPathExpansion(
-          pattern_str, settings_dictionary);
-    }
-
-    if (settings_dictionary) {
-      if (content_type_ == CONTENT_SETTINGS_TYPE_PLUGINS &&
-          !resource_identifier.empty()) {
-        base::DictionaryValue* resource_dictionary = NULL;
-        found = settings_dictionary->GetDictionary(
-            kPerPluginPrefName, &resource_dictionary);
-        if (!found) {
-          if (value == NULL)
-            return;  // Nothing to remove. Exit early.
-          resource_dictionary = new base::DictionaryValue;
-          settings_dictionary->Set(kPerPluginPrefName, resource_dictionary);
-        }
-        // Update resource dictionary.
-        if (value == NULL) {
-          resource_dictionary->RemoveWithoutPathExpansion(resource_identifier,
-                                                          NULL);
-          if (resource_dictionary->empty()) {
-            settings_dictionary->RemoveWithoutPathExpansion(
-                kPerPluginPrefName, NULL);
-          }
-        } else {
-          resource_dictionary->SetWithoutPathExpansion(
-              resource_identifier, value->DeepCopy());
-        }
-      } else {
-        // Update settings dictionary.
-        std::string setting_path = GetTypeName(content_type_);
-        if (value == NULL) {
-          settings_dictionary->RemoveWithoutPathExpansion(setting_path,
-                                                          NULL);
-          settings_dictionary->RemoveWithoutPathExpansion(kLastUsed, NULL);
-        } else {
-          settings_dictionary->SetWithoutPathExpansion(
-              setting_path, value->DeepCopy());
-        }
-      }
-      // Remove the settings dictionary if it is empty.
-      if (settings_dictionary->empty()) {
-        pattern_pairs_settings->RemoveWithoutPathExpansion(
-            pattern_str, NULL);
-      }
-    }
-  }
-}
-
-void ContentSettingsPref::ClearOldPreference() {
-  DCHECK(IsContentSettingsTypeSyncable(content_type_));
-
-  if (*updating_old_preferences_)
-    return;
-
-  std::vector<std::string> keys;
-
-  base::AutoReset<bool> auto_reset(updating_old_preferences_, true);
-  DictionaryPrefUpdate update(prefs_, prefs::kContentSettingsPatternPairs);
-  base::DictionaryValue* old_dictionary = update.Get();
-
-  for (base::DictionaryValue::Iterator it(*old_dictionary);
-       !it.IsAtEnd(); it.Advance()) {
-    keys.push_back(it.key());
-  }
-
-  for (const std::string& key : keys) {
-    base::DictionaryValue* exception;
-    bool is_dictionary =
-        old_dictionary->GetDictionaryWithoutPathExpansion(key, &exception);
-    DCHECK(is_dictionary);
-
-    exception->RemoveWithoutPathExpansion(GetTypeName(content_type_), NULL);
-
-    base::DictionaryValue* last_used;
-    if (exception->GetDictionaryWithoutPathExpansion(kLastUsed, &last_used)) {
-      last_used->RemoveWithoutPathExpansion(GetTypeName(content_type_), NULL);
-
-      if (last_used->empty())
-        exception->RemoveWithoutPathExpansion(kLastUsed, NULL);
-    }
-
-    if (content_type_ == CONTENT_SETTINGS_TYPE_PLUGINS)
-      exception->RemoveWithoutPathExpansion(kPerPluginPrefName, NULL);
-
-    if (exception->empty())
-      old_dictionary->RemoveWithoutPathExpansion(key, NULL);
-  }
-
-}
-
 // static
 void ContentSettingsPref::CanonicalizeContentSettingsExceptions(
     base::DictionaryValue* all_settings_dictionary) {