predictors: Add prefetcher histograms for speculative prefetch.

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 <utility>
 #include <vector>
 
 #include "base/macros.h"
 #include "base/memory/scoped_vector.h"
 #include "base/threading/thread_checker.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:
   // Used to communicate when the prefetching is done. All methods are invoked
   // on the IO thread.
@@ skipping 34 matching lines @@
   // out the Start() call to net::URLRequest for unittesting.
   virtual void StartURLRequest(net::URLRequest* request);
 
   // Marks the request as finished, with the given status.
   void FinishRequest(net::URLRequest* request);
 
   // Reads the response data from the response - required for the resource to
   // be cached correctly. Stubbed out during testing.
   virtual void ReadFullResponse(net::URLRequest* request);
 
+  // Called after successfull reading of response to save stats for histograms.
+  void RequestComplete(net::URLRequest* request);
+
   // net::URLRequest::Delegate methods.
   void OnReceivedRedirect(net::URLRequest* request,
                           const net::RedirectInfo& redirect_info,
                           bool* defer_redirect) override;
   void OnAuthRequired(net::URLRequest* request,
                       net::AuthChallengeInfo* auth_info) override;
   void OnCertificateRequested(
       net::URLRequest* request,
       net::SSLCertRequestInfo* cert_request_info) override;
   void OnSSLCertificateError(net::URLRequest* request,
                              const net::SSLInfo& ssl_info,
                              bool fatal) override;
   void OnResponseStarted(net::URLRequest* request, int net_error) override;
   void OnReadCompleted(net::URLRequest* request, int bytes_read) override;
 
   enum PrefetcherState {
     INITIALIZED = 0,  // Prefetching hasn't started.
     RUNNING = 1,      // Prefetching started, allowed to add more requests.
     STOPPED = 2,      // Prefetching started, not allowed to add more requests.
     FINISHED = 3      // No more inflight request, new requests not possible.
   };
 
   base::ThreadChecker thread_checker_;
   PrefetcherState state_;
   Delegate* const delegate_;
   ResourcePrefetchPredictorConfig const config_;
   GURL main_frame_url_;
-  std::unique_ptr<GURL> urls_;
+
+  // 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_;
 
   DISALLOW_COPY_AND_ASSIGN(ResourcePrefetcher);
 };
 
 }  // namespace predictors
 
 #endif  // CHROME_BROWSER_PREDICTORS_RESOURCE_PREFETCHER_H_