Add trace to the caller of QuotaManager::GetAvailableSpace

storage/browser/quota/quota_callbacks.h

 // Copyright 2013 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 STORAGE_BROWSER_QUOTA_QUOTA_CALLBACKS_H_
 #define STORAGE_BROWSER_QUOTA_QUOTA_CALLBACKS_H_
 
 #include <map>
 #include <set>
 #include <vector>
@@ skipping 42 matching lines @@
     std::vector<CallbackType> callbacks;
     callbacks.swap(callbacks_);
     for (const auto& callback : callbacks)
       callback.Run(base::internal::CallbackForward(args)...);
   }
 
   void Swap(CallbackQueue<CallbackType, Args...>* other) {
     callbacks_.swap(other->callbacks_);
   }
 
+  size_t size() const {
+    return callbacks_.size();
+  }
+
  private:
   std::vector<CallbackType> callbacks_;
 };
 
 template <typename CallbackType, typename Key, typename... Args>
 class CallbackQueueMap {
  public:
   typedef CallbackQueue<CallbackType, Args...> CallbackQueueType;
   typedef std::map<Key, CallbackQueueType> CallbackMap;
   typedef typename CallbackMap::iterator iterator;
@@ skipping 28 matching lines @@
     queue.Run(base::internal::CallbackForward(args)...);
   }
 
  private:
   CallbackMap callback_map_;
 };
 
 }  // namespace storage
 
 #endif  // STORAGE_QUOTA_QUOTA_TYPES_H_