Add UMA to track the number of live URLRequests.

net/url_request/url_request_context.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.
 
 // This class represents contextual information (cookies, cache, etc.)
 // that's necessary when processing resource requests.
 
 #ifndef NET_URL_REQUEST_URL_REQUEST_CONTEXT_H_
 #define NET_URL_REQUEST_URL_REQUEST_CONTEXT_H_
 
@@ skipping 203 matching lines @@
   }
 
   // May return nullptr.
   SdchManager* sdch_manager() const { return sdch_manager_; }
   void set_sdch_manager(SdchManager* sdch_manager) {
     sdch_manager_ = sdch_manager;
   }
 
   // Gets the URLRequest objects that hold a reference to this
   // URLRequestContext.
-  std::set<const URLRequest*>* url_requests() const {
-    return url_requests_.get();
+  const std::set<const URLRequest*>& url_requests() const {
+    return url_requests_;
   }
 
+  void InsertURLRequest(const URLRequest* request) const;
+
+  void RemoveURLRequest(const URLRequest* request) const;
+
   // CHECKs that no URLRequests using this context remain. Subclasses should
   // additionally call AssertNoURLRequests() within their own destructor,
   // prior to implicit destruction of subclass-owned state.
   void AssertNoURLRequests() const;
 
   // Get the underlying |HttpUserAgentSettings| implementation that provides
   // the HTTP Accept-Language and User-Agent header values.
   const HttpUserAgentSettings* http_user_agent_settings() const {
     return http_user_agent_settings_;
   }
@@ skipping 67 matching lines @@
   URLRequestBackoffManager* backoff_manager_;
   SdchManager* sdch_manager_;
   NetworkQualityEstimator* network_quality_estimator_;
   ReportingService* reporting_service_;
 
   // ---------------------------------------------------------------------------
   // Important: When adding any new members below, consider whether they need to
   // be added to CopyFrom.
   // ---------------------------------------------------------------------------
 
-  std::unique_ptr<std::set<const URLRequest*>> url_requests_;
+  mutable std::set<const URLRequest*> url_requests_;
 
   // Enables Brotli Content-Encoding support.
   bool enable_brotli_;
   // Enables checking system policy before allowing a cleartext http or ws
   // request. Only used on Android.
   bool check_cleartext_permitted_;
 
   // An optional name which can be set to describe this URLRequestContext.
   // Used in MemoryDumpProvier to annotate memory usage. The name does not need
   // to be unique.
   const char* name_;
 
+  // The largest number of outstanding URLRequests that have been created by
+  // |this| and are not yet destroyed. This doesn't need to be in CopyFrom.
+  mutable size_t largest_outstanding_requests_count_seen_;
+
   DISALLOW_COPY_AND_ASSIGN(URLRequestContext);
 };
 
 }  // namespace net
 
 #endif  // NET_URL_REQUEST_URL_REQUEST_CONTEXT_H_