Add Null check for kExtensionsPref dictionary...

chrome/browser/extensions/extension_prefs.cc

Index: chrome/browser/extensions/extension_prefs.cc
===================================================================
--- chrome/browser/extensions/extension_prefs.cc	(revision 72910)
+++ chrome/browser/extensions/extension_prefs.cc	(working copy)
@@ -1144,6 +1144,8 @@
   CHECK(out);
   const DictionaryValue* extensions =
       pref_service()->GetDictionary(kExtensionsPref);
+  if (!extensions)
+    return;

[Mattias Nissler (ping if slow), 2011/01/28 09:27:03]

Hm. I'd say that the problem is really with the PrefService code which shouldn't
return NULL in any case here. Could we resolve the report also by replacing this
code in PrefService::GetDictionary():

  const Value* value = pref->GetValue();
  if (value->GetType() == Value::TYPE_NULL)
    return NULL;
  return static_cast<const DictionaryValue*>(value);

by 

  const Value* value = pref->GetValue();
  CHECK(value->IsType(Value::TYPE_DICTIONARY))
  return static_cast<const DictionaryValue*>(value);

[Aaron Boodman, 2011/01/29 19:24:04]

cpu, did you find a case of this actually returning NULL, or did coverity flag
this?

Mattias, what happens if the Preferences file gets changed by hand and the
extensions key gets replaced with some other type? Will PrefService return a
default DictionaryValue or will it return NULL?

 
   for (DictionaryValue::key_iterator ext_id = extensions->begin_keys();
        ext_id != extensions->end_keys(); ++ext_id) {