Fix homepage migration for users who never changed their settings.

chrome/browser/prefs/session_startup_pref.cc

Index: chrome/browser/prefs/session_startup_pref.cc
diff --git a/chrome/browser/prefs/session_startup_pref.cc b/chrome/browser/prefs/session_startup_pref.cc
index 29c6f474b35710d3ccda94805fe2946d870b374c..657d24dd4563c42ea8d0073ae29feeda02416a23 100644
--- a/chrome/browser/prefs/session_startup_pref.cc
+++ b/chrome/browser/prefs/session_startup_pref.cc
@@ -35,10 +35,13 @@ int TypeToPrefValue(SessionStartupPref::Type type) {
 }
 
 void SetNewURLList(PrefService* prefs) {
-  ListValue new_url_pref_list;
-  StringValue* home_page = new StringValue(prefs->GetString(prefs::kHomePage));
-  new_url_pref_list.Append(home_page);
-  prefs->Set(prefs::kURLsToRestoreOnStartup, new_url_pref_list);
+  if (prefs->IsUserModifiablePreference(prefs::kURLsToRestoreOnStartup)) {
+    base::ListValue new_url_pref_list;
+    base::StringValue* home_page =
+        new base::StringValue(prefs->GetString(prefs::kHomePage));
+    new_url_pref_list.Append(home_page);
+    prefs->Set(prefs::kURLsToRestoreOnStartup, new_url_pref_list);
+  }
 }
 
 void URLListToPref(const base::ListValue* url_list, SessionStartupPref* pref) {
@@ -61,6 +64,9 @@ void SessionStartupPref::RegisterUserPrefs(PrefService* prefs) {
                              PrefService::SYNCABLE_PREF);
   prefs->RegisterListPref(prefs::kURLsToRestoreOnStartup,
                           PrefService::SYNCABLE_PREF);
+  prefs->RegisterBooleanPref(prefs::kRestoreOnStartupMigrated,
+                             false,
+                             PrefService::UNSYNCABLE_PREF);
 }
 
 // static
@@ -120,19 +126,12 @@ SessionStartupPref SessionStartupPref::GetStartupPref(Profile* profile) {
 // static
 SessionStartupPref SessionStartupPref::GetStartupPref(PrefService* prefs) {
   DCHECK(prefs);
+
+  MigrateIfNecessary(prefs);
+
   SessionStartupPref pref(
       PrefValueToType(prefs->GetInteger(prefs::kRestoreOnStartup)));
 
-  // Migrate from "Open the home page" to "Open the following URLs". If the user
-  // had the "Open the homepage" option selected, then we need to switch them to
-  // "Open the following URLs" and set the list of URLs to a list containing
-  // just the user's homepage.
-  if (pref.type == SessionStartupPref::HOMEPAGE) {
-    prefs->SetInteger(prefs::kRestoreOnStartup, kPrefValueURLs);
-    pref.type = SessionStartupPref::URLS;
-    SetNewURLList(prefs);
-  }
-
   // Always load the urls, even if the pref type isn't URLS. This way the
   // preferences panels can show the user their last choice.
   const ListValue* url_list = prefs->GetList(prefs::kURLsToRestoreOnStartup);
@@ -142,6 +141,48 @@ SessionStartupPref SessionStartupPref::GetStartupPref(PrefService* prefs) {
 }
 
 // static
+void SessionStartupPref::MigrateIfNecessary(PrefService* prefs) {
+  DCHECK(prefs);
+
+  if (!prefs->GetBoolean(prefs::kRestoreOnStartupMigrated)) {
+    // Read existing values
+    const base::Value* homepage_is_new_tab_page_value =
+        prefs->GetUserPrefValue(prefs::kHomePageIsNewTabPage);
+    bool homepage_is_new_tab_page = true;
+    if (homepage_is_new_tab_page_value)
+      homepage_is_new_tab_page_value->GetAsBoolean(&homepage_is_new_tab_page);
+
+    const base::Value* restore_on_startup_value =
+        prefs->GetUserPrefValue(prefs::kRestoreOnStartup);
+    int restore_on_startup = -1;
+    if (restore_on_startup_value)
+      restore_on_startup_value->GetAsInteger(&restore_on_startup);
+
+    // If restore_on_startup has the deprecated value kPrefValueHomePage,
+    // migrate it to open the homepage on startup. If 'homepage is NTP' is set,
+    // that means just opening the NTP. If not, it means opening a one-item URL
+    // list containing the homepage.
+    if (restore_on_startup == kPrefValueHomePage) {
+      if (homepage_is_new_tab_page) {
+        prefs->SetInteger(prefs::kRestoreOnStartup, kPrefValueNewTab);
+      } else {
+        prefs->SetInteger(prefs::kRestoreOnStartup, kPrefValueURLs);
+        SetNewURLList(prefs);
+      }
+    } else if (!restore_on_startup_value && !homepage_is_new_tab_page) {
+      // kRestoreOnStartup was never set by the user, but the homepage was set.
+      // Migrate to the list of URLs. (If restore_on_startup was never set,
+      // and homepage_is_new_tab_page is true, no action is needed. The new
+      // default value is "open the new tab page" which is what we want.)
+      prefs->SetInteger(prefs::kRestoreOnStartup, kPrefValueURLs);
+      SetNewURLList(prefs);
+    }
+
+    prefs->SetBoolean(prefs::kRestoreOnStartupMigrated, true);
+  }
+}
+
+// static
 bool SessionStartupPref::TypeIsManaged(PrefService* prefs) {
   DCHECK(prefs);
   const PrefService::Preference* pref_restore =