predictors: Key the resource prefetcher by URL, not navigation.

chrome/browser/predictors/resource_prefetcher_manager.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_PREFETCHER_MANAGER_H_
 #define CHROME_BROWSER_PREDICTORS_RESOURCE_PREFETCHER_MANAGER_H_
 
 #include <map>
 #include <memory>
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "chrome/browser/predictors/resource_prefetch_common.h"
 #include "chrome/browser/predictors/resource_prefetcher.h"
 
 namespace net {
 class URLRequestContextGetter;
 }
 
 namespace predictors {
 
 struct NavigationID;
 class ResourcePrefetchPredictor;
 
 // Manages prefetches for multiple navigations.
 //  - Created and owned by the resource prefetch predictor.
 //  - Needs to be refcounted as it is de-referenced on two different threads.
 //  - Created on the UI thread, but most functions are called in the IO thread.
-//  - Will only allow one inflight prefresh per main frame URL.
+//  - Will only allow one inflight prefresh per host.
 class ResourcePrefetcherManager
     :  public ResourcePrefetcher::Delegate,
        public base::RefCountedThreadSafe<ResourcePrefetcherManager> {
  public:
   // The |predictor| should be alive till ShutdownOnIOThread is called.
   ResourcePrefetcherManager(ResourcePrefetchPredictor* predictor,
                             const ResourcePrefetchPredictorConfig& config,
                             net::URLRequestContextGetter* getter);
 
   // UI thread.
   void ShutdownOnUIThread();
 
   // --- IO Thread methods.
 
   // The prefetchers need to be deleted on the IO thread.
   void ShutdownOnIOThread();
 
   // Will create a new ResourcePrefetcher for the main frame url of the input
-  // navigation if there isn't one already for the same URL or host (for host
-  // based).
+  // navigation if there isn't one already for the same host.
   void MaybeAddPrefetch(const NavigationID& navigation_id,
-                        PrefetchKeyType key_type,
                         const std::vector<GURL>& urls);
 
   // Stops the ResourcePrefetcher for the input navigation, if one was in
   // progress.
   void MaybeRemovePrefetch(const NavigationID& navigation_id);
 
   // ResourcePrefetcher::Delegate methods.
   void ResourcePrefetcherFinished(ResourcePrefetcher* prefetcher) override;
   net::URLRequestContext* GetURLRequestContext() override;
 
  private:
   friend class base::RefCountedThreadSafe<ResourcePrefetcherManager>;
   friend class MockResourcePrefetcherManager;
 
   ~ResourcePrefetcherManager() override;
 
   ResourcePrefetchPredictor* predictor_;
   const ResourcePrefetchPredictorConfig config_;
   net::URLRequestContextGetter* const context_getter_;
 
   std::map<std::string, std::unique_ptr<ResourcePrefetcher>> prefetcher_map_;
 
   DISALLOW_COPY_AND_ASSIGN(ResourcePrefetcherManager);
 };
 
 }  // namespace predictors
 
 #endif  // CHROME_BROWSER_PREDICTORS_RESOURCE_PREFETCHER_MANAGER_H_