blink: Cleanup class/struct forward declarations

third_party/WebKit/Source/wtf/HashTable.h

 /*
  * Copyright (C) 2005, 2006, 2007, 2008, 2011, 2012 Apple Inc. All rights
  * reserved.
  * Copyright (C) 2008 David Levin <levin@chromium.org>
  *
  * 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
  * version 2 of the License, or (at your option) any later version.
  *
@@ skipping 68 matching lines @@
   do {                        \
   } while (0)
 #define UPDATE_ACCESS_COUNTS() \
   do {                         \
   } while (0)
 #endif
 #endif
 
 namespace WTF {
 
+// This is for tracing inside collections that have special support for weak
+// pointers. The trait has a trace method which returns true if there are weak
+// pointers to things that have not (yet) been marked live. Returning true
+// indicates that the entry in the collection may yet be removed by weak
+// handling. Default implementation for non-weak types is to use the regular
+// non-weak TraceTrait. Default implementation for types with weakness is to
+// call traceInCollection on the type's trait.
+template <WeakHandlingFlag weakHandlingFlag,
+          ShouldWeakPointersBeMarkedStrongly strongify,
+          typename T,
+          typename Traits>
+struct TraceInCollectionTrait;
+
 #if DUMP_HASHTABLE_STATS
 struct WTF_EXPORT HashTableStats {
   HashTableStats()
       : numAccesses(0),
         numRehashes(0),
         numRemoves(0),
         numReinserts(0),
         maxCollisions(0),
         numCollisions(0),
         collisionGraph() {}
@@ skipping 2161 matching lines @@
   CollectionIterator end(toBeRemoved.end());
   for (CollectionIterator it(toBeRemoved.begin()); it != end; ++it)
     collection.remove(*it);
 }
 
 }  // namespace WTF
 
 #include "wtf/HashIterators.h"
 
 #endif  // WTF_HashTable_h