predictors: Remove unused histograms for speculative_prefetch_predictor.

chrome/browser/predictors/resource_prefetch_predictor.h

 // Copyright 2014 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 CHROME_BROWSER_PREDICTORS_RESOURCE_PREFETCH_PREDICTOR_H_
 #define CHROME_BROWSER_PREDICTORS_RESOURCE_PREFETCH_PREDICTOR_H_
 
 #include <stddef.h>
 
 #include <map>
@@ skipping 196 matching lines @@
 
   // Functions called on different network events pertaining to the loading of
   // main frame resource or sub resources.
   void OnMainFrameRequest(const URLRequestSummary& request);
   void OnMainFrameResponse(const URLRequestSummary& response);
   void OnMainFrameRedirect(const URLRequestSummary& response);
   void OnSubresourceResponse(const URLRequestSummary& response);
 
   // Called when onload completes for a navigation. We treat this point as the
   // "completion" of the navigation. The resources requested by the page up to
-  // this point are the only ones considered for prefetching. Return the page
-  // load time for testing.
-  base::TimeDelta OnNavigationComplete(
-      const NavigationID& nav_id_without_timing_info);
+  // this point are the only ones considered for prefetching.
+  void OnNavigationComplete(const NavigationID& nav_id_without_timing_info);
 
   // Returns true if there is PrefetchData that can be used for the
   // navigation and fills in the |prefetch_data| to resources that need to be
   // prefetched.
   bool GetPrefetchData(const NavigationID& navigation_id,
                        ResourcePrefetcher::RequestVector* prefetch_requests,
                        PrefetchKeyType* key_type);
 
   // Converts a PrefetchData into a ResourcePrefetcher::RequestVector.
   void PopulatePrefetcherRequest(const PrefetchData& data,
@@ skipping 114 matching lines @@
 
   ScopedObserver<history::HistoryService, history::HistoryServiceObserver>
       history_service_observer_;
 
   DISALLOW_COPY_AND_ASSIGN(ResourcePrefetchPredictor);
 };
 
 }  // namespace predictors
 
 #endif  // CHROME_BROWSER_PREDICTORS_RESOURCE_PREFETCH_PREDICTOR_H_