Refactor the API for setting dynamic resource load priorities

Source/core/fetch/Resource.cpp

 /*
     Copyright (C) 1998 Lars Knoll (knoll@mpi-hd.mpg.de)
     Copyright (C) 2001 Dirk Mueller (mueller@kde.org)
     Copyright (C) 2002 Waldo Bastian (bastian@kde.org)
     Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
     Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
 
     This library is free software; you can redistribute it and/or
     modify it under the terms of the GNU Library General Public
     License as published by the Free Software Foundation; either
@@ skipping 936 matching lines @@
     static const int kAverageClientsHashMapSize = 384;
     return sizeof(Resource) + m_response.memoryUsage() + kAverageClientsHashMapSize + m_resourceRequest.url().string().length() * 2;
 }
 
 void Resource::didChangePriority(ResourceLoadPriority loadPriority, int intraPriorityValue)
 {
     if (m_loader)
         m_loader->didChangePriority(loadPriority, intraPriorityValue);
 }
 
+ResourcePriority Resource::priorityFromClients()
+{
+    ResourcePriority priority;
+    ResourceClientWalker<ResourceClient> w(m_clients);
+    while (ResourceClient* c = w.next()) {
+        ResourcePriority nextPriority = c->updatePriority(this);
+        if (nextPriority.visibility == ResourcePriority::NotVisible)
+            continue;
+        priority.visibility = ResourcePriority::Visible;
+        priority.intraPriorityValue += nextPriority.intraPriorityValue;
+    }
+    return priority;
+}
+
 Resource::ResourceCallback* Resource::ResourceCallback::callbackHandler()
 {
     DEFINE_STATIC_LOCAL(OwnPtrWillBePersistent<ResourceCallback>, callbackHandler, (adoptPtrWillBeNoop(new ResourceCallback)));
     return callbackHandler.get();
 }
 
 DEFINE_TRACE(Resource::ResourceCallback)
 {
 #if ENABLE(OILPAN)
     visitor->trace(m_resourcesWithPendingClients);
@@ skipping 135 matching lines @@
         return "ImportResource";
     case Resource::Media:
         return "Media";
     }
     ASSERT_NOT_REACHED();
     return "Unknown";
 }
 #endif // !LOG_DISABLED
 
 } // namespace blink