predictors: Add prefetching hit/miss histograms.

chrome/browser/predictors/resource_prefetcher.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_H_
 #define CHROME_BROWSER_PREDICTORS_RESOURCE_PREFETCHER_H_
 
 #include <stddef.h>
 
 #include <list>
 #include <map>
 #include <memory>
+#include <string>
 #include <utility>
 #include <vector>
 
 #include "base/macros.h"
 #include "base/memory/scoped_vector.h"
 #include "base/threading/thread_checker.h"
+#include "base/time/time.h"
 #include "chrome/browser/predictors/resource_prefetch_common.h"
 #include "net/url_request/redirect_info.h"
 #include "net/url_request/url_request.h"
 #include "url/gurl.h"
 
 namespace net {
 class URLRequestContext;
 }
 
 namespace predictors {
 
 namespace internal {
 constexpr char kResourcePrefetchPredictorCachePatternHistogram[] =
     "ResourcePrefetchPredictor.CachePattern";
 constexpr char kResourcePrefetchPredictorPrefetchedCountHistogram[] =
     "ResourcePrefetchPredictor.PrefetchedCount";
 constexpr char kResourcePrefetchPredictorPrefetchedSizeHistogram[] =
     "ResourcePrefetchPredictor.PrefetchedSizeKB";
 }  // namespace internal
 
 // Responsible for prefetching resources for a single main frame URL based on
 // the input list of resources.
 //  - Limits the max number of resources in flight for any host and also across
 //    hosts.
 //  - When stopped, will wait for the pending requests to finish.
 //  - Lives entirely on the IO thread.
 class ResourcePrefetcher : public net::URLRequest::Delegate {
  public:
+  struct PrefetchedRequestStats {
+    PrefetchedRequestStats(const GURL& resource_url,
+                           bool was_cached,
+                           size_t total_received_bytes);
+    ~PrefetchedRequestStats();
+
+    GURL resource_url;
+    bool was_cached;
+    size_t total_received_bytes;
+  };
+
+  struct PrefetcherStats {
+    explicit PrefetcherStats(const GURL& url);
+    ~PrefetcherStats();
+    PrefetcherStats(const PrefetcherStats& other);
+
+    GURL url;
+    base::TimeTicks start_time;
+    std::vector<PrefetchedRequestStats> requests_stats;
+  };
+
   // Used to communicate when the prefetching is done. All methods are invoked
   // on the IO thread.
   class Delegate {
    public:
     virtual ~Delegate() { }
 
     // Called when the ResourcePrefetcher is finished, i.e. there is nothing
     // pending in flight.
-    virtual void ResourcePrefetcherFinished(ResourcePrefetcher* prefetcher) = 0;
+    virtual void ResourcePrefetcherFinished(ResourcePrefetcher* prefetcher,
+                                            const PrefetcherStats& stats) = 0;
 
     virtual net::URLRequestContext* GetURLRequestContext() = 0;
   };
 
   // |delegate| has to outlive the ResourcePrefetcher.
   ResourcePrefetcher(Delegate* delegate,
                      const ResourcePrefetchPredictorConfig& config,
                      const GURL& main_frame_url,
                      const std::vector<GURL>& urls);
   ~ResourcePrefetcher() override;
@@ skipping 56 matching lines @@
   GURL main_frame_url_;
 
   // For histogram reports.
   size_t prefetched_count_;
   int64_t prefetched_bytes_;
 
   std::map<net::URLRequest*, std::unique_ptr<net::URLRequest>>
       inflight_requests_;
   std::list<GURL> request_queue_;
   std::map<std::string, size_t> host_inflight_counts_;
+  PrefetcherStats stats_;
 
   DISALLOW_COPY_AND_ASSIGN(ResourcePrefetcher);
 };
 
 }  // namespace predictors
 
 #endif  // CHROME_BROWSER_PREDICTORS_RESOURCE_PREFETCHER_H_