Avoid duplicates in SPDY's write blocked list.

net/quic/quic_write_blocked_list.h

 // 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.
 //
 #ifndef NET_QUIC_QUIC_WRITE_BLOCKED_LIST_H_
 #define NET_QUIC_QUIC_WRITE_BLOCKED_LIST_H_
 
 #include <set>
 
 #include "net/base/net_export.h"
 #include "net/quic/quic_protocol.h"
 #include "net/spdy/write_blocked_list.h"
 
 namespace net {
 
 // Keeps tracks of the QUIC streams that have data to write, sorted by
 // priority.  QUIC stream priority order is:
 // Crypto stream > Headers stream > Data streams by requested priority.
 class NET_EXPORT_PRIVATE QuicWriteBlockedList {
  private:
   typedef WriteBlockedList<QuicStreamId> QuicWriteBlockedListBase;
 
  public:
   static const QuicPriority kHighestPriority;
   static const QuicPriority kLowestPriority;
 
-  QuicWriteBlockedList();
+  explicit QuicWriteBlockedList(bool avoid_duplicate_streams);
   ~QuicWriteBlockedList();
 
   bool HasWriteBlockedDataStreams() const {
     return base_write_blocked_list_.HasWriteBlockedStreams();
   }
 
   bool HasWriteBlockedCryptoOrHeadersStream() const {
     return crypto_stream_blocked_ || headers_stream_blocked_;
   }
 
@@ skipping 35 matching lines @@
       return;
     }
 
     if (stream_id == kHeadersStreamId) {
       DCHECK_EQ(kHighestPriority, priority);
       // TODO(avd) Add DCHECK(!headers_stream_blocked_);
       headers_stream_blocked_ = true;
       return;
     }
 
-    if (blocked_streams_.find(stream_id) != blocked_streams_.end()) {
+    if (!base_write_blocked_list_.avoids_inserting_duplicates() &&
+        blocked_streams_.find(stream_id) != blocked_streams_.end()) {
       DVLOG(1) << "Stream " << stream_id << " already in write blocked list.";
       return;
     }
 
     base_write_blocked_list_.PushBack(
         stream_id, static_cast<SpdyPriority>(priority));
     blocked_streams_.insert(stream_id);
     return;
   }
 
@@ skipping 10 matching lines @@
   // should mirror the contents of base_write_blocked_list_.
   std::set<QuicStreamId> blocked_streams_;
 
   DISALLOW_COPY_AND_ASSIGN(QuicWriteBlockedList);
 };
 
 }  // namespace net
 
 
 #endif  // NET_QUIC_QUIC_WRITE_BLOCKED_LIST_H_