Add migration from old to new NTP Promo pref structure.

ios/chrome/browser/notification_promo.cc

 // Copyright (c) 2016 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 "ios/chrome/browser/notification_promo.h"
 
 #include <stddef.h>
 
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
 #include "base/time/time.h"
 #include "base/values.h"
 #include "components/pref_registry/pref_registry_syncable.h"
 #include "components/prefs/pref_registry_simple.h"
 #include "components/prefs/pref_service.h"
 #include "components/variations/variations_associated_data.h"
 
 namespace ios {
 
 namespace {
 
 const char kNTPPromoFinchExperiment[] = "IOSNTPPromotion";
 
 // The name of the preference that stores the promotion object.
 const char kPrefPromoObject[] = "ios.ntppromo";
 
 // Keys in the kPrefPromoObject dictionary; used only here.
+const char kPrefPromoID[] = "id";
 const char kPrefPromoFirstViewTime[] = "first_view_time";
 const char kPrefPromoViews[] = "views";
 const char kPrefPromoClosed[] = "closed";
 
 }  // namespace
 
 NotificationPromo::NotificationPromo(PrefService* local_state)
     : local_state_(local_state),
       promo_type_(NO_PROMO),
       promo_payload_(new base::DictionaryValue()),
@@ skipping 90 matching lines @@
     user_prefs::PrefRegistrySyncable* registry) {
   registry->RegisterDictionaryPref(kPrefPromoObject);
 }
 
 // static
 void NotificationPromo::MigrateUserPrefs(PrefService* user_prefs) {
   user_prefs->ClearPref(kPrefPromoObject);
 }
 
 void NotificationPromo::WritePrefs() {
+  WritePrefs(promo_id_, first_view_time_, views_, closed_);
+}
+
+void NotificationPromo::WritePrefs(int promo_id,
+                                   double first_view_time,
+                                   int views,
+                                   bool closed) {
   base::DictionaryValue* ntp_promo = new base::DictionaryValue;
-  ntp_promo->SetDouble(kPrefPromoFirstViewTime, first_view_time_);
-  ntp_promo->SetInteger(kPrefPromoViews, views_);
-  ntp_promo->SetBoolean(kPrefPromoClosed, closed_);
+  ntp_promo->SetDouble(kPrefPromoFirstViewTime, first_view_time);
+  ntp_promo->SetInteger(kPrefPromoViews, views);
+  ntp_promo->SetBoolean(kPrefPromoClosed, closed);
 
   base::DictionaryValue promo_dict;
   promo_dict.MergeDictionary(local_state_->GetDictionary(kPrefPromoObject));
-  promo_dict.Set(base::IntToString(promo_id_), ntp_promo);
+  promo_dict.Set(base::IntToString(promo_id), ntp_promo);
   local_state_->Set(kPrefPromoObject, promo_dict);
   DVLOG(1) << "WritePrefs " << promo_dict;
 }
 
 void NotificationPromo::InitFromPrefs(PromoType promo_type) {
   promo_type_ = promo_type;
 
+  // Check if data is stored in the old prefs structure, and migrate it before
+  // reading from prefs.
+  MigrateOldPrefs();
+
   // If |promo_id_| is not set, do nothing.
   if (promo_id_ == -1)
     return;
 
   const base::DictionaryValue* promo_dict =
       local_state_->GetDictionary(kPrefPromoObject);
   if (!promo_dict)
     return;
 
   const base::DictionaryValue* ntp_promo = NULL;
   promo_dict->GetDictionary(base::IntToString(promo_id_), &ntp_promo);
   if (!ntp_promo)
     return;
 
   ntp_promo->GetDouble(kPrefPromoFirstViewTime, &first_view_time_);
   ntp_promo->GetInteger(kPrefPromoViews, &views_);
   ntp_promo->GetBoolean(kPrefPromoClosed, &closed_);
 }
 
+void NotificationPromo::MigrateOldPrefs() {
+  const base::DictionaryValue* promo_dict =
+      local_state_->GetDictionary(kPrefPromoObject);
+  if (!promo_dict)
+    return;
+
+  const base::ListValue* promo_list = NULL;
+  promo_dict->GetList("mobile_ntp_whats_new_promo", &promo_list);
+  if (!promo_list)
+    return;
+
+  const base::DictionaryValue* ntp_promo = NULL;
+  promo_list->GetDictionary(0, &ntp_promo);
+  if (!ntp_promo) {
+    // If the list is saved but there is no promo dictionary, clear prefs to
+    // delete the empty list.
+    NotificationPromo::MigrateUserPrefs(local_state_);
+    return;
+  }
+
+  int promo_id = -1;
+  ntp_promo->GetInteger(kPrefPromoID, &promo_id);
+  if (promo_id == -1) {
+    // If there is no promo id saved in prefs, then data is corrupt and the
+    // prefs can be discarded.
+    NotificationPromo::MigrateUserPrefs(local_state_);
+    return;
+  }
+
+  double first_view_time = 0;
+  ntp_promo->GetDouble(kPrefPromoFirstViewTime, &first_view_time);
+  int views = 0;
+  ntp_promo->GetInteger(kPrefPromoViews, &views);
+  bool closed = false;
+  ntp_promo->GetBoolean(kPrefPromoClosed, &closed);
+
+  // Clear prefs to discard the old structure before saving the data in the new
+  // structure.
+  NotificationPromo::MigrateUserPrefs(local_state_);
+  WritePrefs(promo_id, first_view_time, views, closed);
+}
+
 bool NotificationPromo::CanShow() const {
   return !closed_ && !promo_text_.empty() && !ExceedsMaxViews() &&
          !ExceedsMaxSeconds() &&
          base::Time::FromDoubleT(StartTime()) < base::Time::Now() &&
          base::Time::FromDoubleT(EndTime()) > base::Time::Now();
 }
 
 void NotificationPromo::HandleClosed() {
   if (!closed_) {
     closed_ = true;
@@ skipping 45 matching lines @@
 
 double NotificationPromo::StartTime() const {
   return start_;
 }
 
 double NotificationPromo::EndTime() const {
   return end_;
 }
 
 }  // namespace ios