Fix homepage migration for users who never changed their settings.

chrome/test/functional/protector.py

Index: chrome/test/functional/protector.py
diff --git a/chrome/test/functional/protector.py b/chrome/test/functional/protector.py
index c7f432d03b66f5b3f843a6905683699209a1d0af..9b62d8a5b81a8338d6baf14cf82b3743665bd324 100755
--- a/chrome/test/functional/protector.py
+++ b/chrome/test/functional/protector.py
@@ -151,21 +151,30 @@ class BaseProtectorTest(pyauto.PyUITest):
     prefs['backup']['_signature'] = 'INVALID'
     self._WritePreferences(prefs)
 
-  def _ChangeSessionStartupPrefs(self, startup_type, startup_urls=None,
-                                 homepage=None):
+  def _ChangeSessionStartupPrefs(self, startup_type=None, startup_urls=None,
+                                 homepage=None, delete_migrated_pref=False):
     """Changes the session startup type and the list of URLs to load on startup.
 
     Args:
-      startup_type: int with one of _SESSION_STARTUP_* values.
+      startup_type: int with one of _SESSION_STARTUP_* values. If startup_type
+          is None, then it deletes the preference.
       startup_urls: list(str) with a list of URLs; if None, is left unchanged.
       homepage: unless None, the new value for homepage.
+      delete_migrated_pref: Whether we should delete the preference which says
+          we've already migrated the startup_type preference.
     """
     prefs = self._LoadPreferences()
-    prefs['session']['restore_on_startup'] = startup_type
+    if startup_type is None:
+      del prefs['session']['restore_on_startup']
+    else:
+      prefs['session']['restore_on_startup'] = startup_type
+
     if startup_urls is not None:
       prefs['session']['urls_to_restore_on_startup'] = startup_urls
     if homepage is not None:
       prefs['homepage'] = homepage
+    if delete_migrated_pref:
+      del prefs['session']['restore_on_startup_migrated']
     self._WritePreferences(prefs)
 
   def _ChangePinnedTabsPrefs(self, pinned_tabs):
@@ -452,7 +461,7 @@ class ProtectorSessionStartupTest(BaseProtectorTest):
     # No longer showing the change.
     self.assertFalse(self.GetProtectorState()['showing_change'])
 
-  def testSessionStartupPrefMigration(self):
+  def testSessionStartupPrefMigrationFromHomepage(self):
     """Test migration from old session.restore_on_startup values (homepage)."""
     # Set startup prefs to restoring last open tabs.
     self.SetPrefs(pyauto.kRestoreOnStartup, self._SESSION_STARTUP_LAST)
@@ -463,7 +472,8 @@ class ProtectorSessionStartupTest(BaseProtectorTest):
         clear_profile=False,
         pre_launch_hook=lambda: self._ChangeSessionStartupPrefs(
             self._SESSION_STARTUP_HOMEPAGE,
-            homepage=new_homepage))
+            homepage=new_homepage,
+            delete_migrated_pref=True))
     # The change must be detected by Protector.
     self.assertTrue(self.GetProtectorState()['showing_change'])
     # Protector must restore old preference values.
@@ -481,6 +491,63 @@ class ProtectorSessionStartupTest(BaseProtectorTest):
     # No longer showing the change.
     self.assertFalse(self.GetProtectorState()['showing_change'])
 
+  def testSessionStartupPrefMigrationFromBlank(self):
+    """Test migration from session.restore_on_startup being blank, as it would
+    be for a user who had m18 or lower, and never changed that preference.
+    """
+    # Set startup prefs to restoring last open tabs.
+    self.SetPrefs(pyauto.kRestoreOnStartup, self._SESSION_STARTUP_LAST)
+    self.SetPrefs(pyauto.kURLsToRestoreOnStartup, [])
+    # Set the homepage.
+    new_homepage = 'http://www.google.com/'
+    self.SetPrefs(pyauto.kHomePageIsNewTabPage, False)
+    self.SetPrefs(pyauto.kHomePage, new_homepage)
+    # Restart browser, clearing the 'restore on startup' pref, to simulate a
+    # user coming from m18 and having left it on the default value.
+    self.RestartBrowser(
+        clear_profile=False,
+        pre_launch_hook=lambda: self._ChangeSessionStartupPrefs(
+            startup_type=None,
+            delete_migrated_pref=True))
+    # The change must be detected by Protector.
+    self.assertTrue(self.GetProtectorState()['showing_change'])
+    # Protector must restore old preference values.
+    self.assertEqual(self._SESSION_STARTUP_LAST,
+                     self.GetPrefsInfo().Prefs(pyauto.kRestoreOnStartup))
+    self.assertEqual([],
+                     self.GetPrefsInfo().Prefs(pyauto.kURLsToRestoreOnStartup))
+    self.ApplyProtectorChange()
+    # Now the new preference values are active.
+    self.assertEqual(self._SESSION_STARTUP_URLS,
+                     self.GetPrefsInfo().Prefs(pyauto.kRestoreOnStartup))
+    # Homepage migrated to the list of startup URLs.
+    self.assertEqual([new_homepage],
+                     self.GetPrefsInfo().Prefs(pyauto.kURLsToRestoreOnStartup))
+    # No longer showing the change.
+    self.assertFalse(self.GetProtectorState()['showing_change'])
+
+  def testSessionStartupPrefNoMigrationOnHomepageChange(self):
+    """Test that when the user modifies their homepage in m19+, we don't do the
+    preference migration.
+    """
+    # Initially, the default value is selected for kRestoreOnStartup.
+    self.assertEqual(self._SESSION_STARTUP_NTP,
+                     self.GetPrefsInfo().Prefs(pyauto.kRestoreOnStartup))
+    # Set the homepage, but leave kRestoreOnStartup unchanged.
+    new_homepage = 'http://www.google.com/'
+    self.SetPrefs(pyauto.kHomePageIsNewTabPage, False)
+    self.SetPrefs(pyauto.kHomePage, new_homepage)
+    # Restart browser.
+    self.RestartBrowser(clear_profile=False)
+    # Now the new preference values are active.
+    self.assertEqual(self._SESSION_STARTUP_NTP,
+                     self.GetPrefsInfo().Prefs(pyauto.kRestoreOnStartup))
+    # kURLsToRestoreOnStartup pref is unchanged.
+    self.assertEqual([],
+                     self.GetPrefsInfo().Prefs(pyauto.kURLsToRestoreOnStartup))
+    # No longer showing the change.
+    self.assertFalse(self.GetProtectorState()['showing_change'])
+
   def testDetectPinnedTabsChangeAndApply(self):
     """Test for detecting and applying a change to pinned tabs."""
     pinned_urls = ['chrome://version/', 'chrome://credits/']