Add a cap of six in-flight requests per host to the ResourceScheduler

net/base/priority_queue.h

 // 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.
 
 #ifndef NET_BASE_PRIORITY_QUEUE_H_
 #define NET_BASE_PRIORITY_QUEUE_H_
 
 #include <list>
 #include <vector>
 
@@ skipping 246 matching lines @@
     DCHECK(CalledOnValidThread());
     for (size_t i = 0; i < lists_.size(); ++i) {
       lists_[i].clear();
     }
 #if !defined(NDEBUG)
     valid_ids_.clear();
 #endif
     size_ = 0u;
   }
 
+  // This can be used to iterate through the composite container, in
+  // highest-to-lowest, first-inserted-to-last order.
+  Pointer NextHighest(const Pointer& previous) {
+    Priority priority = previous.priority_;
+    typename Pointer::ListIterator list_entry = previous.iterator_;
+
+    if (list_entry != lists_[priority].end()) {
+      ++list_entry;
+    }
+
+    while (priority < lists_.size()) {
+      if (list_entry == lists_[priority].end()) {
+        if (priority == 0) {
+          break;
+        }
+        priority--;
+        list_entry = lists_[priority].begin();
+      } else {
+        return Pointer(priority, list_entry);
+      }
+    }
+
+    return Pointer();
+  }
+
   // Returns the number of priorities the queue supports.
   size_t num_priorities() const {
     DCHECK(CalledOnValidThread());
     return lists_.size();
   }
 
   bool empty() const {
     DCHECK(CalledOnValidThread());
     return size_ == 0;
   }
@@ skipping 14 matching lines @@
 
   ListVector lists_;
   size_t size_;
 
   DISALLOW_COPY_AND_ASSIGN(PriorityQueue);
 };
 
 }  // namespace net
 
 #endif  // NET_BASE_PRIORITY_QUEUE_H_