[Sync] Remove unnecessary DCHECK in pref model associator.

We assumed that when a preference becomes unmanaged, it will be user
controlled as well. This isn't the case if it was a default value previously.
This gets handled properly in the association code though, so just remove the
DCHECK and make the comment clearer.

BUG=97611
TEST=unit_tests --gtest_filter="*ProfileSyncServicePreference*"


Review URL: http://codereview.chromium.org/8266001

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@105379 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 31 insertions, 4 deletions

diff --git a/chrome/browser/prefs/pref_model_associator.cc b/chrome/browser/prefs/pref_model_associator.cc
index b61e511..1928331 100644
--- a/chrome/browser/prefs/pref_model_associator.cc
+++ b/chrome/browser/prefs/pref_model_associator.cc
@@ -412,10 +412,9 @@ void PrefModelAssociator::ProcessPrefChange(const std::string& name) {
   AutoReset<bool> processing_changes(&processing_syncer_changes_, true);
 
   if (synced_preferences_.count(name) == 0) {
-    DCHECK(preference->IsUserControlled());
-    // This preference was previously not user controlled and there was no sync
-    // data, but is now user controlled. We must associate it and create a sync
-    // node for it.
+    // Not in synced_preferences_ means no synced data. InitPrefAndAssociate(..)
+    // will determine if we care about its data (e.g. if it has a default value
+    // and hasn't been changed yet we don't) and take care syncing any new data.
     InitPrefAndAssociate(SyncData(), name, &changes);
   } else {
     // We are already syncing this preference, just update it's sync node.
diff --git a/chrome/browser/sync/profile_sync_service_preference_unittest.cc b/chrome/browser/sync/profile_sync_service_preference_unittest.cc
index af3367f..1c5b08e 100644
--- a/chrome/browser/sync/profile_sync_service_preference_unittest.cc
+++ b/chrome/browser/sync/profile_sync_service_preference_unittest.cc
@@ -539,3 +539,31 @@ TEST_F(ProfileSyncServicePreferenceTest,
   // Sync value should be picked up.
   EXPECT_TRUE(sync_value->Equals(&GetPreferenceValue(prefs::kHomePage)));
 }
+
+TEST_F(ProfileSyncServicePreferenceTest, DynamicManagedDefaultPreferences) {
+  const PrefService::Preference* pref =
+      prefs_->FindPreference(prefs::kHomePage);
+  EXPECT_TRUE(pref->IsDefaultValue());
+  CreateRootTask task(this, syncable::PREFERENCES);
+  ASSERT_TRUE(StartSyncService(&task, false));
+  ASSERT_TRUE(task.success());
+  EXPECT_TRUE(IsSynced(prefs::kHomePage));
+  EXPECT_TRUE(pref->IsDefaultValue());
+  EXPECT_TRUE(GetSyncedValue(prefs::kHomePage) == NULL);
+  // Switch kHomePage to managed and set a different value.
+  scoped_ptr<Value> managed_value(
+      Value::CreateStringValue("http://example.com/managed"));
+  profile_->GetTestingPrefService()->SetManagedPref(
+      prefs::kHomePage, managed_value->DeepCopy());
+  // The pref value should be the one dictated by policy.
+  EXPECT_TRUE(managed_value->Equals(&GetPreferenceValue(prefs::kHomePage)));
+  EXPECT_FALSE(pref->IsDefaultValue());
+  // There should be no synced value.
+  EXPECT_TRUE(GetSyncedValue(prefs::kHomePage) == NULL);
+  // Switch kHomePage back to unmanaged.
+  profile_->GetTestingPrefService()->RemoveManagedPref(prefs::kHomePage);
+  // The original value should be picked up.
+  EXPECT_TRUE(pref->IsDefaultValue());
+  // There should still be no synced value.
+  EXPECT_TRUE(GetSyncedValue(prefs::kHomePage) == NULL);
+}