Fix homepage migration for users who never changed their settings.

chrome/browser/prefs/pref_service.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/prefs/pref_service.h"
 
 #include <algorithm>
 #include <string>
 
 #include "base/bind.h"
@@ skipping 666 matching lines @@
     return NULL;
   }
   const Value* value = pref->GetValue();
   if (value->GetType() != Value::TYPE_DICTIONARY) {
     NOTREACHED();
     return NULL;
   }
   return static_cast<const DictionaryValue*>(value);
 }
 
+const base::Value* PrefService::GetUserPrefValue(const char* path) const {
+  DCHECK(CalledOnValidThread());
+
+  const Preference* pref = FindPreference(path);
+  if (!pref) {
+    NOTREACHED() << "Trying to get an unregistered pref: " << path;
+    return NULL;
+  }
+
+  // Look for an existing preference in the user store. If it doesn't
+  // exist, return NULL.
+  base::Value* value = NULL;
+  if (user_pref_store_->GetMutableValue(path, &value) !=
+          PersistentPrefStore::READ_OK) {
+    return NULL;
+  }
+
+  if (!value->IsType(pref->GetType())) {
+    NOTREACHED() << "Pref value type doesn't match registered type.";
+    return NULL;
+  }
+
+  return value;
+}
+
 const ListValue* PrefService::GetList(const char* path) const {
   DCHECK(CalledOnValidThread());
 
   const Preference* pref = FindPreference(path);
   if (!pref) {
     NOTREACHED() << "Trying to read an unregistered pref: " << path;
     return NULL;
   }
   const Value* value = pref->GetValue();
   if (value->GetType() != Value::TYPE_LIST) {
@@ skipping 258 matching lines @@
   return pref_value_store()->PrefValueFromDefaultStore(name_.c_str());
 }
 
 bool PrefService::Preference::IsUserModifiable() const {
   return pref_value_store()->PrefValueUserModifiable(name_.c_str());
 }
 
 bool PrefService::Preference::IsExtensionModifiable() const {
   return pref_value_store()->PrefValueExtensionModifiable(name_.c_str());
 }