Remove the migration code from content_settings::DefaultProvider.

The migration of default content settings from one dictionary pref into individual prefs appeared in M43. The next branchpoint is M46. After three versions, it is safe to remove the migration code.

Question: What happens to users who weren't migrated during this time (i.e. jump from M<43 to M>=46)?
Answer: Their content settings will be reset, since their individual prefs will not be populated. However, their profile won't be damaged; the old dictionary will be simply ignored. Thus, the user will have their settings restored to default values, as if in a new profile. For the more sensitive settings, the user will be asked before a permission is granted to the site; however, for cookies, images and javascript the default value is to allow websites to use them.

TESTED=Change in the settings UI was correctly reflected in the same window, in incognito window, and for synced settings also on a synced computer.

BUG=452388

Review URL: https://codereview.chromium.org/1252973002

Cr-Commit-Position: refs/heads/master@{#340475}

4 files changed, 61 insertions, 245 deletions

diff --git a/components/content_settings/core/browser/content_settings_default_provider.cc b/components/content_settings/core/browser/content_settings_default_provider.cc
index 0bf7514..6adccfd 100644
--- a/components/content_settings/core/browser/content_settings_default_provider.cc
+++ b/components/content_settings/core/browser/content_settings_default_provider.cc
@@ -28,6 +28,13 @@ namespace content_settings {
 
 namespace {
 
+// Obsolete prefs to be removed from the pref file.
+// TODO(msramek): Remove this cleanup code after two releases (i.e. in M48).
+const char kObsoleteDefaultContentSettings[] =
+    "profile.default_content_settings";
+const char kObsoleteMigratedDefaultContentSettings[] =
+    "profile.migrated_default_content_settings";
+
 struct DefaultContentSettingInfo {
   // The profile preference associated with this default setting.
   const char* pref_name;
@@ -107,38 +114,32 @@ class DefaultRuleIterator : public RuleIterator {
 // static
 void DefaultProvider::RegisterProfilePrefs(
     user_prefs::PrefRegistrySyncable* registry) {
-  // The registration of the preference prefs::kDefaultContentSettings should
-  // also include the default values for default content settings. This allows
-  // functional tests to get default content settings by reading the preference
-  // prefs::kDefaultContentSettings via pyauto.
-  // TODO(markusheintz): Write pyauto hooks for the content settings map as
-  // content settings should be read from the host content settings map.
-  base::DictionaryValue* default_content_settings = new base::DictionaryValue();
-  registry->RegisterDictionaryPref(
-      prefs::kDefaultContentSettings,
-      default_content_settings,
-      user_prefs::PrefRegistrySyncable::SYNCABLE_PREF);
-
-  // Register individual default setting preferences.
-  // TODO(msramek): The aggregate preference above is deprecated. Remove it
-  // after two stable releases.
+  // Register the default settings' preferences.
   for (int i = 0; i < CONTENT_SETTINGS_NUM_TYPES; ++i) {
     ContentSettingsType type = static_cast<ContentSettingsType>(i);
     registry->RegisterIntegerPref(GetPrefName(type), GetDefaultValue(type),
                                   PrefRegistrationFlagsForType(type));
   }
 
+  // Whether the deprecated mediastream default setting has already been
+  // migrated into microphone and camera default settings.
+  registry->RegisterBooleanPref(prefs::kMigratedDefaultMediaStreamSetting,
+                                false);
+
+  // Obsolete prefs -------------------------------------------------------
+
+  // The deprecated dictionary preference.
+  registry->RegisterDictionaryPref(
+      kObsoleteDefaultContentSettings,
+      new base::DictionaryValue(),
+      user_prefs::PrefRegistrySyncable::SYNCABLE_PREF);
+
   // Whether the deprecated dictionary preference has already been migrated
   // into the individual preferences in this profile.
   registry->RegisterBooleanPref(
-      prefs::kMigratedDefaultContentSettings,
+      kObsoleteMigratedDefaultContentSettings,
       false,
       user_prefs::PrefRegistrySyncable::SYNCABLE_PREF);
-
-  // Whether the deprecated mediastream default setting has already been
-  // migrated into microphone and camera default settings.
-  registry->RegisterBooleanPref(prefs::kMigratedDefaultMediaStreamSetting,
-                                false);
 }
 
 DefaultProvider::DefaultProvider(PrefService* prefs, bool incognito)
@@ -147,13 +148,8 @@ DefaultProvider::DefaultProvider(PrefService* prefs, bool incognito)
       updating_preferences_(false) {
   DCHECK(prefs_);
 
-  // Migrate the dictionary of default content settings to the new individual
-  // preferences.
-  MigrateDefaultSettings();
-
-  // Migrate the obsolete media stream default setting into the new microphone
-  // and camera settings.
-  MigrateObsoleteMediaContentSetting();
+  // Remove the obsolete preferences from the pref file.
+  DiscardObsoletePreferences();
 
   // Read global defaults.
   ReadDefaultSettings();
@@ -217,8 +213,6 @@ DefaultProvider::DefaultProvider(PrefService* prefs, bool incognito)
   pref_change_registrar_.Init(prefs_);
   PrefChangeRegistrar::NamedChangeCallback callback = base::Bind(
       &DefaultProvider::OnPreferenceChanged, base::Unretained(this));
-  pref_change_registrar_.Add(prefs::kDefaultContentSettings, callback);
-
   for (int i = 0; i < CONTENT_SETTINGS_NUM_TYPES; ++i) {
     ContentSettingsType type = static_cast<ContentSettingsType>(i);
     pref_change_registrar_.Add(GetPrefName(type), callback);
@@ -261,13 +255,7 @@ bool DefaultProvider::SetWebsiteSetting(
       base::AutoLock lock(lock_);
       ChangeSetting(content_type, value.get());
     }
-    WriteIndividualPref(content_type, value.get());
-
-    // If the changed setting is syncable, write it to the old dictionary
-    // preference as well, so it can be synced to older versions of Chrome.
-    // TODO(msramek): Remove this after two stable releases.
-    if (IsContentSettingsTypeSyncable(content_type))
-      WriteDictionaryPref(content_type, value.get());
+    WriteToPref(content_type, value.get());
   }
 
   NotifyObservers(ContentSettingsPattern(),
@@ -313,7 +301,7 @@ void DefaultProvider::ReadDefaultSettings() {
   base::AutoLock lock(lock_);
   for (int i = 0; i < CONTENT_SETTINGS_NUM_TYPES; ++i) {
     ContentSettingsType type = static_cast<ContentSettingsType>(i);
-    ChangeSetting(type, ReadIndividualPref(type).get());
+    ChangeSetting(type, ReadFromPref(type).get());
   }
 }
 
@@ -333,8 +321,8 @@ void DefaultProvider::ChangeSetting(ContentSettingsType content_type,
   }
 }
 
-void DefaultProvider::WriteIndividualPref(ContentSettingsType content_type,
-                                          base::Value* value) {
+void DefaultProvider::WriteToPref(ContentSettingsType content_type,
+                                  base::Value* value) {
   if (IsValueEmptyOrDefault(content_type, value)) {
     prefs_->ClearPref(GetPrefName(content_type));
     return;
@@ -346,145 +334,53 @@ void DefaultProvider::WriteIndividualPref(ContentSettingsType content_type,
   prefs_->SetInteger(GetPrefName(content_type), int_value);
 }
 
-void DefaultProvider::WriteDictionaryPref(ContentSettingsType content_type,
-                                          base::Value* value) {
-  // |DefaultProvider| should not send any notifications when holding
-  // |lock_|. |DictionaryPrefUpdate| destructor and
-  // |PrefService::SetInteger()| send out notifications. As a response, the
-  // upper layers may call |GetAllContentSettingRules| which acquires |lock_|
-  // again.
-  DictionaryPrefUpdate update(prefs_, prefs::kDefaultContentSettings);
-  base::DictionaryValue* default_settings_dictionary = update.Get();
-
-  if (IsValueEmptyOrDefault(content_type, value)) {
-    default_settings_dictionary->RemoveWithoutPathExpansion(
-        GetTypeName(content_type), NULL);
-    return;
-  }
-
-  default_settings_dictionary->SetWithoutPathExpansion(
-      GetTypeName(content_type), value->DeepCopy());
-}
-
 void DefaultProvider::OnPreferenceChanged(const std::string& name) {
   DCHECK(CalledOnValidThread());
   if (updating_preferences_)
     return;
 
-  // Write the changed setting from individual preferences to dictionary,
-  // or vice versa - depending on which of them changed.
-  // TODO(msramek): This is only necessary in the phase of migration between
-  // the old dictionary preference and the new individual preferences. Remove
-  // this after two stable releases.
-  std::vector<ContentSettingsType> to_notify;
-
-  if (name == prefs::kDefaultContentSettings) {
-    // If the dictionary preference gets synced from an old version
-    // of Chrome, we should update all individual preferences that
-    // are marked as syncable.
-    base::AutoReset<bool> auto_reset(&updating_preferences_, true);
-
-    scoped_ptr<ValueMap> dictionary = ReadDictionaryPref();
+  // Find out which content setting the preference corresponds to.
+  ContentSettingsType content_type = CONTENT_SETTINGS_TYPE_DEFAULT;
 
-    // Lock the memory map access, so that values are not read by
-    // |GetRuleIterator| at the same time as they are written here. Do not lock
-    // the preference access though; preference updates send out notifications
-    // whose callbacks may try to reacquire the lock on the same thread.
-    {
-      base::AutoLock lock(lock_);
-      for (const auto& it : *dictionary) {
-        if (!IsContentSettingsTypeSyncable(it.first))
-          continue;
-
-        DCHECK(default_settings_.find(it.first) != default_settings_.end());
-        ChangeSetting(it.first, it.second.get());
-        to_notify.push_back(it.first);
-      }
-    }
-
-    // When the lock is released, write the new settings to preferences.
-    for (const auto& it : *dictionary) {
-      if (!IsContentSettingsTypeSyncable(it.first))
-        continue;
-      WriteIndividualPref(it.first, it.second.get());
-    }
-  } else {
-    // Find out which content setting the preference corresponds to.
-    ContentSettingsType content_type = CONTENT_SETTINGS_TYPE_DEFAULT;
-
-    for (int i = 0; i < CONTENT_SETTINGS_NUM_TYPES; ++i) {
-      ContentSettingsType type = static_cast<ContentSettingsType>(i);
-      if (GetPrefName(type) == name) {
-        content_type = type;
-        break;
-      }
+  for (int i = 0; i < CONTENT_SETTINGS_NUM_TYPES; ++i) {
+    ContentSettingsType type = static_cast<ContentSettingsType>(i);
+    if (GetPrefName(type) == name) {
+      content_type = type;
+      break;
     }
+  }
 
-    if (content_type == CONTENT_SETTINGS_TYPE_DEFAULT) {
-      NOTREACHED() << "Unexpected preference observed";
-      return;
-    }
+  if (content_type == CONTENT_SETTINGS_TYPE_DEFAULT) {
+    NOTREACHED() << "A change of the preference " << name << " was observed, "
+                    "but the preference could not be mapped to a content "
+                    "settings type.";
+    return;
+  }
 
-    // A new individual preference is changed. If it is syncable, we should
-    // change its entry in the dictionary preference as well, so that it
-    // can be synced to older versions of Chrome.
+  {
     base::AutoReset<bool> auto_reset(&updating_preferences_, true);
-
     // Lock the memory map access, so that values are not read by
     // |GetRuleIterator| at the same time as they are written here. Do not lock
     // the preference access though; preference updates send out notifications
     // whose callbacks may try to reacquire the lock on the same thread.
     {
       base::AutoLock lock(lock_);
-      ChangeSetting(content_type, ReadIndividualPref(content_type).get());
+      ChangeSetting(content_type, ReadFromPref(content_type).get());
     }
-    if (IsContentSettingsTypeSyncable(content_type))
-      WriteDictionaryPref(content_type, default_settings_[content_type].get());
-    to_notify.push_back(content_type);
   }
 
-  for (const ContentSettingsType content_type : to_notify) {
-    NotifyObservers(ContentSettingsPattern(),
-                    ContentSettingsPattern(),
-                    content_type,
-                    ResourceIdentifier());
-  }
+  NotifyObservers(ContentSettingsPattern(),
+                  ContentSettingsPattern(),
+                  content_type,
+                  ResourceIdentifier());
 }
 
-scoped_ptr<base::Value> DefaultProvider::ReadIndividualPref(
+scoped_ptr<base::Value> DefaultProvider::ReadFromPref(
     ContentSettingsType content_type) {
   int int_value = prefs_->GetInteger(GetPrefName(content_type));
   return ContentSettingToValue(IntToContentSetting(int_value)).Pass();
 }
 
-scoped_ptr<DefaultProvider::ValueMap> DefaultProvider::ReadDictionaryPref() {
-  const base::DictionaryValue* default_settings_dictionary =
-      prefs_->GetDictionary(prefs::kDefaultContentSettings);
-
-  scoped_ptr<ValueMap> value_map =
-      GetSettingsFromDictionary(default_settings_dictionary);
-
-  ForceDefaultsToBeExplicit(value_map.get());
-
-  // Migrate obsolete cookie prompt mode.
-  if (ValueToContentSetting(
-          (*value_map)[CONTENT_SETTINGS_TYPE_COOKIES].get()) ==
-      CONTENT_SETTING_ASK) {
-    (*value_map)[CONTENT_SETTINGS_TYPE_COOKIES].reset(
-        new base::FundamentalValue(CONTENT_SETTING_BLOCK));
-  }
-#if defined(OS_ANDROID) || defined(OS_CHROMEOS)
-  // Migrate protected media from allow to ask.
-  if (ValueToContentSetting(
-          (*value_map)[CONTENT_SETTINGS_TYPE_PROTECTED_MEDIA_IDENTIFIER]
-              .get()) == CONTENT_SETTING_ALLOW) {
-    (*value_map)[CONTENT_SETTINGS_TYPE_PROTECTED_MEDIA_IDENTIFIER].reset(
-        new base::FundamentalValue(CONTENT_SETTING_ASK));
-  }
-#endif
-  return value_map.Pass();
-}
-
 void DefaultProvider::ForceDefaultsToBeExplicit(ValueMap* value_map) {
   for (int i = 0; i < CONTENT_SETTINGS_NUM_TYPES; ++i) {
     ContentSettingsType type = static_cast<ContentSettingsType>(i);
@@ -495,58 +391,9 @@ void DefaultProvider::ForceDefaultsToBeExplicit(ValueMap* value_map) {
   }
 }
 
-scoped_ptr<DefaultProvider::ValueMap>
-    DefaultProvider::GetSettingsFromDictionary(
-        const base::DictionaryValue* dictionary) {
-  scoped_ptr<ValueMap> value_map(new ValueMap());
-  if (!dictionary)
-    return value_map.Pass();
-
-  for (base::DictionaryValue::Iterator i(*dictionary);
-       !i.IsAtEnd(); i.Advance()) {
-    const std::string& content_type(i.key());
-    for (int type = 0; type < CONTENT_SETTINGS_NUM_TYPES; ++type) {
-      if (content_type == GetTypeName(ContentSettingsType(type))) {
-        int int_value = CONTENT_SETTING_DEFAULT;
-        bool is_integer = i.value().GetAsInteger(&int_value);
-        DCHECK(is_integer);
-        (*value_map)[ContentSettingsType(type)].reset(
-            ContentSettingToValue(IntToContentSetting(int_value)).release());
-        break;
-      }
-    }
-  }
-
-  return value_map.Pass();
-}
-
-void DefaultProvider::MigrateDefaultSettings() {
-  // Only do the migration once.
-  if (prefs_->GetBoolean(prefs::kMigratedDefaultContentSettings))
-    return;
-
-  scoped_ptr<DefaultProvider::ValueMap> value_map = ReadDictionaryPref();
-
-  for (int i = 0; i < CONTENT_SETTINGS_NUM_TYPES; ++i) {
-    ContentSettingsType type = static_cast<ContentSettingsType>(i);
-    WriteIndividualPref(type, (*value_map)[type].get());
-  }
-
-  prefs_->SetBoolean(prefs::kMigratedDefaultContentSettings, true);
-}
-
-void DefaultProvider::MigrateObsoleteMediaContentSetting() {
-  // We only do the migration once.
-  if (prefs_->GetBoolean(prefs::kMigratedDefaultMediaStreamSetting))
-    return;
-
-  scoped_ptr<base::Value> value = ReadIndividualPref(
-      CONTENT_SETTINGS_TYPE_MEDIASTREAM);
-  WriteIndividualPref(CONTENT_SETTINGS_TYPE_MEDIASTREAM_MIC, value.get());
-  WriteIndividualPref(CONTENT_SETTINGS_TYPE_MEDIASTREAM_CAMERA, value.get());
-  WriteIndividualPref(CONTENT_SETTINGS_TYPE_MEDIASTREAM, NULL);
-
-  prefs_->SetBoolean(prefs::kMigratedDefaultMediaStreamSetting, true);
+void DefaultProvider::DiscardObsoletePreferences() {
+  prefs_->ClearPref(kObsoleteDefaultContentSettings);
+  prefs_->ClearPref(kObsoleteMigratedDefaultContentSettings);
 }
 
 }  // namespace content_settings
diff --git a/components/content_settings/core/browser/content_settings_default_provider.h b/components/content_settings/core/browser/content_settings_default_provider.h
index 86ec1c8..52b668c 100644
--- a/components/content_settings/core/browser/content_settings_default_provider.h
+++ b/components/content_settings/core/browser/content_settings_default_provider.h
@@ -53,7 +53,7 @@ class DefaultProvider : public ObservableProvider {
   typedef linked_ptr<base::Value> ValuePtr;
   typedef std::map<ContentSettingsType, ValuePtr> ValueMap;
 
-  // Reads all individual settings from the pref service.
+  // Reads all settings from the pref service.
   void ReadDefaultSettings();
 
   // Change the remembered setting in the memory.
@@ -63,43 +63,23 @@ class DefaultProvider : public ObservableProvider {
   bool IsValueEmptyOrDefault(ContentSettingsType content_type,
                              base::Value* value);
 
-  // Parses a |DictionaryValue| into a |ValueMap|.
-  scoped_ptr<ValueMap> GetSettingsFromDictionary(
-      const base::DictionaryValue* dictionary);
-
   // Forces the default settings in |value_map| to be explicitly set instead
   // of themselves being CONTENT_SETTING_DEFAULT.
   void ForceDefaultsToBeExplicit(ValueMap* value_map);
 
-  // Reads the dictionary prefrence and returns the dictionary parsed as
-  // a |ValueMap|.
-  scoped_ptr<ValueMap> ReadDictionaryPref();
-
-  // Reads an individual preference.
-  scoped_ptr<base::Value> ReadIndividualPref(ContentSettingsType content_type);
+  // Reads the preference corresponding to |content_type|.
+  scoped_ptr<base::Value> ReadFromPref(ContentSettingsType content_type);
 
-  // Writes the value |value| to the individual preference corresponding
-  // to |content_type|. It's the responsibility of caller to obtain a lock
-  // and notify observers.
-  void WriteIndividualPref(ContentSettingsType content_type,
-                           base::Value* value);
-
-  // Writes the value |value| to the dictionary preference entry corresponding
-  // to |content_type|. It's the responsibility of caller to obtain a lock
-  // and notify observers.
-  void WriteDictionaryPref(ContentSettingsType content_type,
-                           base::Value* value);
+  // Writes the value |value| to the preference corresponding to |content_type|.
+  // It's the responsibility of caller to obtain a lock and notify observers.
+  void WriteToPref(ContentSettingsType content_type,
+                   base::Value* value);
 
   // Called on prefs change.
   void OnPreferenceChanged(const std::string& pref_name);
 
-  // Migrates the dictionary settings to the individual settings. Only called
-  // once during the first run.
-  void MigrateDefaultSettings();
-
-  // Migrates the obsolete media stream default setting to the new microphone
-  // and camera settings.
-  void MigrateObsoleteMediaContentSetting();
+  // Clean up the obsolete preferences from the user's profile.
+  void DiscardObsoletePreferences();
 
   // Copies of the pref data, so that we can read it on the IO thread.
   ValueMap default_settings_;
diff --git a/components/content_settings/core/common/pref_names.cc b/components/content_settings/core/common/pref_names.cc
index 71818e2..4c0ffb2 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";
-
 // Preferences storing the default values for individual content settings.
 const char kDefaultCookiesSetting[] =
     "profile.default_content_setting_values.cookies";
diff --git a/components/content_settings/core/common/pref_names.h b/components/content_settings/core/common/pref_names.h
index 67fa3e7..c7ee72d 100644
--- a/components/content_settings/core/common/pref_names.h
+++ b/components/content_settings/core/common/pref_names.h
@@ -13,8 +13,6 @@ extern const char kBlockThirdPartyCookies[];
 extern const char kContentSettingsVersion[];
 extern const char kContentSettingsPatternPairs[];
 extern const char kContentSettingsWindowLastTabIndex[];
-extern const char kDefaultContentSettings[];
-extern const char kMigratedDefaultContentSettings[];
 
 extern const char kDefaultCookiesSetting[];
 extern const char kDefaultImagesSetting[];