Merge 132468 - [NTP4] Fix empty apps page crash.

chrome/browser/extensions/extension_sorting.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/extensions/extension_sorting.h"
 
 #include "chrome/browser/extensions/extension_scoped_prefs.h"
 #include "chrome/browser/extensions/extension_service.h"
 #include "chrome/common/chrome_notification_types.h"
 #include "content/public/browser/notification_service.h"
@@ skipping 29 matching lines @@
   extension_service_ = extension_service;
 }
 
 void ExtensionSorting::Initialize(
     const ExtensionPrefs::ExtensionIdSet& extension_ids) {
   InitializePageOrdinalMap(extension_ids);
 
   MigrateAppIndex(extension_ids);
 }
 
+void ExtensionSorting::CreateOrdinalsIfNecessary(size_t minimum_size) {
+  // Create StringOrdinal values as required to ensure |ntp_ordinal_map_| has at
+  // least |minimum_size| entries.
+  if (ntp_ordinal_map_.empty() && minimum_size > 0)
+    ntp_ordinal_map_[StringOrdinal::CreateInitialOrdinal()];
+
+  while (ntp_ordinal_map_.size() < minimum_size) {
+    StringOrdinal filler = ntp_ordinal_map_.rbegin()->first.CreateAfter();
+    ntp_ordinal_map_[filler];
+  }
+}
+
 void ExtensionSorting::MigrateAppIndex(
     const ExtensionPrefs::ExtensionIdSet& extension_ids) {
   if (extension_ids.empty())
     return;
 
   // Convert all the page index values to page ordinals. If there are any
   // app launch values that need to be migrated, inserted them into a sorted
   // set to be dealt with later.
   typedef std::map<StringOrdinal, std::map<int, const std::string*>,
       StringOrdinalLessThan> AppPositionToIdMapping;
   AppPositionToIdMapping app_launches_to_convert;
   for (ExtensionPrefs::ExtensionIdSet::const_iterator ext_id =
            extension_ids.begin(); ext_id != extension_ids.end(); ++ext_id) {
     int old_page_index = 0;
     StringOrdinal page = GetPageOrdinal(*ext_id);
     if (extension_scoped_prefs_->ReadExtensionPrefInteger(
             *ext_id,
             kPrefPageIndexDeprecated,
             &old_page_index)) {
       // Some extensions have invalid page index, so we don't
       // attempt to convert them.
       if (old_page_index < 0) {
         DLOG(WARNING) << "Extension " << *ext_id
                       << " has an invalid page index " << old_page_index
                       << ". Aborting attempt to convert its index.";
         break;
       }
 
-      // Since we require all earlier StringOrdinals to already exist in order
-      // to properly convert from integers and we are iterating though them in
-      // no given order, we create earlier StringOrdinal values as required.
-      // This should be filled in by the time we are done with this loop.
-      if (ntp_ordinal_map_.empty())
-        ntp_ordinal_map_[StringOrdinal::CreateInitialOrdinal()];
-      while (ntp_ordinal_map_.size()
-             <= static_cast<size_t>(old_page_index)) {
-        StringOrdinal earlier_page =
-            ntp_ordinal_map_.rbegin()->first.CreateAfter();
-        ntp_ordinal_map_[earlier_page];
-      }
+      CreateOrdinalsIfNecessary(static_cast<size_t>(old_page_index) + 1);
 
       page = PageIntegerAsStringOrdinal(old_page_index);
       SetPageOrdinal(*ext_id, page);
       extension_scoped_prefs_->UpdateExtensionPref(
           *ext_id, kPrefPageIndexDeprecated, NULL);
     }
 
     int old_app_launch_index = 0;
     if (extension_scoped_prefs_->ReadExtensionPrefInteger(
             *ext_id,
@@ skipping 160 matching lines @@
   extension_scoped_prefs_->ReadExtensionPrefString(
       extension_id, kPrefAppLaunchOrdinal, &raw_value);
   return StringOrdinal(raw_value);
 }
 
 void ExtensionSorting::SetAppLaunchOrdinal(
     const std::string& extension_id,
     const StringOrdinal& new_app_launch_ordinal) {
   // No work is required if the old and new values are the same.
   if (new_app_launch_ordinal.EqualOrBothInvalid(
-          GetAppLaunchOrdinal(extension_id)))
+          GetAppLaunchOrdinal(extension_id))) {
     return;
+  }
 
   StringOrdinal page_ordinal = GetPageOrdinal(extension_id);
   RemoveOrdinalMapping(
       extension_id, page_ordinal, GetAppLaunchOrdinal(extension_id));
   AddOrdinalMapping(extension_id, page_ordinal, new_app_launch_ordinal);
 
   Value* new_value = new_app_launch_ordinal.IsValid() ?
       Value::CreateStringValue(new_app_launch_ordinal.ToString()) :
       NULL;
 
@@ skipping 104 matching lines @@
 int ExtensionSorting::PageStringOrdinalAsInteger(
     const StringOrdinal& page_ordinal) const {
   if (!page_ordinal.IsValid())
     return -1;
 
   PageOrdinalMap::const_iterator it = ntp_ordinal_map_.find(page_ordinal);
   return it != ntp_ordinal_map_.end() ?
       std::distance(ntp_ordinal_map_.begin(), it) : -1;
 }
 
-StringOrdinal ExtensionSorting::PageIntegerAsStringOrdinal(size_t page_index)
-    const {
-  // We shouldn't have a page_index that is more than 1 position away from the
-  // current end.
-  CHECK_LE(page_index, ntp_ordinal_map_.size());
-
+StringOrdinal ExtensionSorting::PageIntegerAsStringOrdinal(size_t page_index) {
   const DictionaryValue* extensions = pref_service_->GetDictionary(
           ExtensionPrefs::kExtensionsPref);
+
   if (!extensions)
     return StringOrdinal();
 
   if (page_index < ntp_ordinal_map_.size()) {
     PageOrdinalMap::const_iterator it = ntp_ordinal_map_.begin();
     std::advance(it, page_index);
+    return it->first;
+  }
 
-    return it->first;
-
-  } else {
-    if (ntp_ordinal_map_.empty())
-      return StringOrdinal::CreateInitialOrdinal();
-    else
-      return ntp_ordinal_map_.rbegin()->first.CreateAfter();
-  }
+  CreateOrdinalsIfNecessary(page_index + 1);
+  return ntp_ordinal_map_.rbegin()->first;
 }
 
 StringOrdinal ExtensionSorting::GetMinOrMaxAppLaunchOrdinalsOnPage(
     const StringOrdinal& target_page_ordinal,
     AppLaunchOrdinalReturn return_type) const {
   CHECK(target_page_ordinal.IsValid());
 
   StringOrdinal return_value;
 
   PageOrdinalMap::const_iterator page =
@@ skipping 78 matching lines @@
     if (ext) {
       // It is possible for old extension to have ordinal values, but they
       // shouldn't so we clear them.
       if (!ext->is_app())
         ClearOrdinals(extension_id);
 
       extension_service_->SyncExtensionChangeIfNeeded(*ext);
     }
   }
 }