Add migration from old to new NTP Promo pref structure.

ios/chrome/browser/notification_promo_unittest.cc

Index: ios/chrome/browser/notification_promo_unittest.cc
diff --git a/ios/chrome/browser/notification_promo_unittest.cc b/ios/chrome/browser/notification_promo_unittest.cc
index 642836a3d3478d7e1e1bd10159b019e49fc5d491..6040f2a9d08cf3cc3e299315a7358d8a80d29e6e 100644
--- a/ios/chrome/browser/notification_promo_unittest.cc
+++ b/ios/chrome/browser/notification_promo_unittest.cc
@@ -288,6 +288,40 @@ class NotificationPromoTest : public testing::Test {
     notification_promo_.WritePrefs();
   }
 
+  // Tests that if data is saved in the old pref structure, it is successfully
+  // migrated to the new structure that supports saving multiple promos.
+  void TestMigrationOfOldPrefs() {
+    NotificationPromo promo(&local_state_);
+    promo.InitFromVariations();
+
+    // Pick values for each variable that is saved into old prefs structure.
+    double first_view_time = 2.0;
+    int views = max_views_ + 1;
+    bool closed = true;
+
+    // Save data into old prefs structure.
+    base::DictionaryValue* ntp_promo = new base::DictionaryValue;
+    ntp_promo->SetInteger("id", promo.promo_id_);
+    ntp_promo->SetDouble("first_view_time", first_view_time);
+    ntp_promo->SetInteger("views", views);
+    ntp_promo->SetBoolean("closed", true);
+
+    base::ListValue* promo_list = new base::ListValue;
+    promo_list->Set(0, ntp_promo);
+
+    base::DictionaryValue promo_dict;
+    promo_dict.Set("mobile_ntp_whats_new_promo", promo_list);
+    local_state_.Set("ios.ntppromo", promo_dict);
+
+    // Initialize promo and verify that its instance variables match the data

[rohitrao (ping after 24h), 2016/06/27 17:04:19]

Also verify that the old prefs are gone?

[gchatz, 2016/06/27 23:12:22]

Added check for this.

+    // saved in the old structure.
+    promo.InitFromPrefs(promo_type_);
+    EXPECT_EQ(first_view_time, promo.first_view_time_);
+    EXPECT_EQ(views, promo.views_);
+    EXPECT_EQ(closed, promo.closed_);
+    EXPECT_FALSE(promo.CanShow());
+  }
+
   const NotificationPromo& promo() const { return notification_promo_; }
 
  protected:
@@ -375,4 +409,26 @@ TEST_F(NotificationPromoTest, NotificationPromoFinchTest) {
   TestFirstViewTimeRecorded();
 }
 
+TEST_F(NotificationPromoTest, NotificationPromoPrefMigrationTest) {
+  Init(
+      "{"
+      "  \"start\":\"3 Aug 1999 9:26:06 GMT\","
+      "  \"end\":\"$1\","
+      "  \"promo_text\":\"What do you think of Chrome?\","
+      "  \"payload\":"
+      "    {"
+      "      \"days_active\":7,"
+      "      \"install_age_days\":21"
+      "    },"
+      "  \"max_views\":30,"
+      "  \"max_seconds\":30,"
+      "  \"promo_id\":0"
+      "}",
+      "What do you think of Chrome?",
+      933672366,  // unix epoch for 3 Aug 1999 9:26:06 GMT.
+      0, 30, 30);
+  InitPromoFromVariations();
+  TestMigrationOfOldPrefs();
+}
+
 }  // namespace ios