Sort headers for iteration

third_party/WebKit/Source/modules/fetch/Headers.cpp

 // Copyright 2014 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 "modules/fetch/Headers.h"
 
 #include "bindings/core/v8/Dictionary.h"
 #include "bindings/core/v8/ExceptionState.h"
 #include "bindings/core/v8/V8IteratorResultValue.h"
 #include "core/dom/Iterator.h"
 #include "core/fetch/FetchUtils.h"
 #include "wtf/NotFound.h"
 #include "wtf/PassRefPtr.h"
 #include "wtf/RefPtr.h"
 #include "wtf/text/WTFString.h"
 
 namespace blink {
 
 namespace {
 
 class HeadersIterationSource final
     : public PairIterable<String, String>::IterationSource {
  public:
-  explicit HeadersIterationSource(FetchHeaderList* headers)
-      : m_headers(headers), m_current(0) {}
+  explicit HeadersIterationSource(const FetchHeaderList* headers)
+      : m_headers(headers->clone()), m_current(0) {
+    m_headers->sortAndCombine();
+  }
 
   bool next(ScriptState* scriptState,
             String& key,
             String& value,
             ExceptionState& exception) override {
-    // FIXME: This simply advances an index and returns the next value if
-    // any, so if the iterated object is mutated values may be skipped.
+    // This simply advances an index and returns the next value if any; the
+    // iterated list is not exposed to script so it will never be mutated
+    // during iteration.
     if (m_current >= m_headers->size())
       return false;
 
     const FetchHeaderList::Header& header = m_headers->entry(m_current++);
     key = header.first;
     value = header.second;
     return true;
   }
 
   DEFINE_INLINE_VIRTUAL_TRACE() {
@@ skipping 274 matching lines @@
   visitor->trace(m_headerList);
 }
 
 PairIterable<String, String>::IterationSource* Headers::startIteration(
     ScriptState*,
     ExceptionState&) {
   return new HeadersIterationSource(m_headerList);
 }
 
 }  // namespace blink