Add histograms to gather ResourceScheduler information.

content/browser/loader/resource_scheduler.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 CONTENT_BROWSER_LOADER_RESOURCE_SCHEDULER_H_
 #define CONTENT_BROWSER_LOADER_RESOURCE_SCHEDULER_H_
 
 #include <map>
 #include <set>
 
@@ skipping 133 matching lines @@
   void OnReceivedSpdyProxiedHttpResponse(int child_id, int route_id);
 
   // Client functions:
 
   // Called to check if all user observable tabs have completed loading.
   bool active_clients_loaded() const { return active_clients_loading_ == 0; }
 
   bool IsClientVisibleForTesting(int child_id, int route_id);
 
  private:
+  enum ClientState {
+    // Observable client.
+    ACTIVE,
+    // Non-observable client.
+    BACKGROUND,
+    // No client found.
+    UNKNOWN,
+  };
+
   class RequestQueue;
   class ScheduledResourceRequest;
   struct RequestPriorityParams;
   struct ScheduledResourceSorter {
     bool operator()(const ScheduledResourceRequest* a,
                     const ScheduledResourceRequest* b) const;
   };
   class Client;
 
   typedef int64 ClientId;
@@ skipping 17 matching lines @@
 
   // Called when a Client becomes coalesced.
   void IncrementCoalescedClients();
   // Called when a client stops being coalesced.
   void DecrementCoalescedClients();
 
   void LoadCoalescedRequests();
 
   size_t CountCoalescedClients() const;
 
+  // Returns UNKNOWN if the corresponding client is not found, else returns
+  // whether the client is ACTIVE (user-observable) or BACKGROUND.
+  ClientState GetClientState(ClientId client_id) const;
+
   // Update the queue position for |request|, possibly causing it to start
   // loading.
   //
   // Queues are maintained for each priority level. When |request| is
   // reprioritized, it will move to the end of the queue for that priority
   // level.
   void ReprioritizeRequest(ScheduledResourceRequest* request,
                            net::RequestPriority new_priority,
                            int intra_priority_value);
 
   // Returns the client ID for the given |child_id| and |route_id| combo.
   ClientId MakeClientId(int child_id, int route_id);
 
   // Returns the client for the given |child_id| and |route_id| combo.
   Client* GetClient(int child_id, int route_id);
 
   bool should_coalesce_;
   bool should_throttle_;
   ClientMap client_map_;
   size_t active_clients_loading_;
   size_t coalesced_clients_;
   // This is a repeating timer to initiate requests on COALESCED Clients.
   scoped_ptr<base::Timer> coalescing_timer_;
   RequestSet unowned_requests_;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_LOADER_RESOURCE_SCHEDULER_H_