Allow partial update for notification update API

chrome/browser/notifications/balloon_collection_base.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/notifications/balloon_collection_base.h"
 
 #include "base/stl_util.h"
 #include "chrome/browser/notifications/balloon.h"
 #include "chrome/browser/notifications/notification.h"
 #include "url/gurl.h"
@@ skipping 17 matching lines @@
   scoped_ptr<Balloon> to_delete(balloon);
   Balloons::iterator iter;
   for (iter = balloons_.begin(); iter != balloons_.end(); ++iter) {
     if ((*iter) == balloon) {
       balloons_.erase(iter);
       return;
     }
   }
 }
 
-bool BalloonCollectionBase::DoesIdExist(const std::string& id) {
-  Balloons::iterator iter;
+const Notification* BalloonCollectionBase::FindById(
+    const std::string& id) const {
+  Balloons::const_iterator iter;
   for (iter = balloons_.begin(); iter != balloons_.end(); ++iter) {
-    if ((*iter)->notification().notification_id() == id)
-      return true;
+    if ((*iter)->notification().notification_id() == id) {
+      return &((*iter)->notification());
+    }
   }
-  return false;
+  return NULL;
 }
 
 bool BalloonCollectionBase::CloseById(const std::string& id) {
   // Use a local list of balloons to close to avoid breaking
   // iterator changes on each close.
   Balloons to_close;
   Balloons::iterator iter;
   for (iter = balloons_.begin(); iter != balloons_.end(); ++iter) {
     if ((*iter)->notification().notification_id() == id)
       to_close.push_back(*iter);
@@ skipping 51 matching lines @@
     if ((*iter)->notification().notification_id() == notification_id) {
       return *iter;
     }
   }
   return NULL;
 }
 
 Balloon* BalloonCollectionBase::FindBalloon(const Notification& notification) {
   return FindBalloonById(notification.notification_id());
 }