Fix a crash during extension installation (debug only)....

chrome/browser/extensions/external_pref_extension_provider.cc

Index: chrome/browser/extensions/external_pref_extension_provider.cc
===================================================================
--- chrome/browser/extensions/external_pref_extension_provider.cc	(revision 18397)
+++ chrome/browser/extensions/external_pref_extension_provider.cc	(working copy)
@@ -66,11 +66,8 @@
 Version* ExternalPrefExtensionProvider::RegisteredVersion(
     std::string id, Extension::Location* location) const {
   DictionaryValue* extension = NULL;
-  if (!prefs_->GetDictionary(ASCIIToWide(id), &extension)) {
-    NOTREACHED() << "Cannot read extension " << id.c_str()
-                 << " from dictionary.";
+  if (!prefs_->GetDictionary(ASCIIToWide(id), &extension))
     return NULL;
-  }
 
   std::string external_version;
   if (!extension->GetString(kExternalVersion, &external_version))