predictors: Add browsertest that tests prefetching.

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 141 matching lines @@
   void RecordMainFrameLoadComplete(const NavigationID& navigation_id);
 
   // Starts prefetching if it is enabled for |origin| and prefetching data
   // exists for the |main_frame_url| either at the URL or at the host level.
   void StartPrefetching(const GURL& main_frame_url, PrefetchOrigin origin);
 
   // Stops prefetching that may be in progress corresponding to
   // |main_frame_url|.
   void StopPrefetching(const GURL& main_frame_url);
 
+  // Called when ResourcePrefetcher is finished, i.e. there is nothing pending
+  // in flight.
+  void OnPrefetchingFinished(const GURL& main_frame_url);
+
   // Sets the |observer| to be notified when the resource prefetch predictor
   // data changes. Previously registered observer will be discarded. Call
   // this with nullptr parameter to de-register observer.
   void SetObserverForTesting(TestObserver* observer);
 
  private:
   friend class ::PredictorsHandler;
   friend class ResourcePrefetchPredictorTest;
   friend class ResourcePrefetchPredictorBrowserTest;
 
@@ skipping 187 matching lines @@
 // has changed. All methods are invoked on the UI thread.
 class TestObserver {
  public:
   // De-registers itself from |predictor_| on destruction.
   virtual ~TestObserver();
 
   virtual void OnNavigationLearned(
       size_t url_visit_count,
       const ResourcePrefetchPredictor::PageRequestSummary& summary) {}
 
+  virtual void OnPrefetchingFinished(const GURL& main_frame_url) {}
+
   virtual void OnPredictorInitialized() {}
 
  protected:
   // |predictor| must be non-NULL and has to outlive the TestObserver.
   // Also the predictor must not have a TestObserver set.
   explicit TestObserver(ResourcePrefetchPredictor* predictor);
 
  private:
   ResourcePrefetchPredictor* predictor_;
 
   DISALLOW_COPY_AND_ASSIGN(TestObserver);
 };
 
 }  // namespace predictors
 
 #endif  // CHROME_BROWSER_PREDICTORS_RESOURCE_PREFETCH_PREDICTOR_H_