Fix for Bug 50726 "Save extension list and "winning" prefs from extensions"

chrome/browser/prefs/pref_value_store.cc

Index: chrome/browser/prefs/pref_value_store.cc
diff --git a/chrome/browser/prefs/pref_value_store.cc b/chrome/browser/prefs/pref_value_store.cc
index 84b6919ec7067db82354d49ea8596d67b7c1a504..987f99871a00d1f5b9adb5435fdd1ca5170dd58d 100644
--- a/chrome/browser/prefs/pref_value_store.cc
+++ b/chrome/browser/prefs/pref_value_store.cc
@@ -56,7 +56,7 @@ PrefValueStore* PrefValueStore::CreatePrefValueStore(
     device_management =
         ConfigurationPolicyPrefStore::CreateDeviceManagementPolicyPrefStore(
             profile);
-    extension = new ExtensionPrefStore(profile, PrefNotifier::EXTENSION_STORE);
+    extension = new ExtensionPrefStore(profile);
     command_line = new CommandLinePrefStore(CommandLine::ForCurrentProcess());
     recommended =
         ConfigurationPolicyPrefStore::CreateRecommendedPolicyPrefStore();
@@ -148,13 +148,19 @@ bool PrefValueStore::HasPrefPath(const char* path) const {
 bool PrefValueStore::PrefHasChanged(const char* path,
                                     PrefNotifier::PrefStoreType new_store) {
   DCHECK(new_store != PrefNotifier::INVALID_STORE);
+  // If we get a change notification about an unregistered preference,
+  // discard it silently because there cannot be any listeners.
+  if (pref_types_.find(path) == pref_types_.end())
+    return false;
+
   // Replying that the pref has changed may cause problems, but it's the safer
   // choice.
   if (new_store == PrefNotifier::INVALID_STORE)
     return true;
 
   PrefNotifier::PrefStoreType controller = ControllingPrefStoreForPref(path);
-  DCHECK(controller != PrefNotifier::INVALID_STORE);
+  DCHECK(controller != PrefNotifier::INVALID_STORE)
+      << "Invalid controller for path " << path;
   if (controller == PrefNotifier::INVALID_STORE)
     return true;