Run load state update timer only when needed

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 132 matching lines @@
   // from a proxy using SPDY.
   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);
 
+  // Returns true if at least one client is currently loading.
+  bool HasLoadingClients() const;
+
  private:
   enum ClientState {
     // Observable client.
     ACTIVE,
     // Non-observable client.
     BACKGROUND,
     // No client found.
     UNKNOWN,
   };
 
@@ skipping 60 matching lines @@
   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_