predictors: Add RedirectStatus histogram + fix redirects related bug.

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 41 matching lines @@
 constexpr char kResourcePrefetchPredictorPrefetchMissesCountNotCached[] =
     "ResourcePrefetchPredictor.PrefetchMissesCount.NotCached";
 constexpr char kResourcePrefetchPredictorPrefetchHitsCountCached[] =
     "ResourcePrefetchPredictor.PrefetchHitsCount.Cached";
 constexpr char kResourcePrefetchPredictorPrefetchHitsCountNotCached[] =
     "ResourcePrefetchPredictor.PrefetchHitsCount.NotCached";
 constexpr char kResourcePrefetchPredictorPrefetchHitsSize[] =
     "ResourcePrefetchPredictor.PrefetchHitsSizeKB";
 constexpr char kResourcePrefetchPredictorPrefetchMissesSize[] =
     "ResourcePrefetchPredictor.PrefetchMissesSizeKB";
+constexpr char kResourcePrefetchPredictorRedirectStatusHistogram[] =
+    "ResourcePrefetchPredictor.RedirectStatus";
 }  // namespace internal
 
 class TestObserver;
 class ResourcePrefetcherManager;
 
 // Contains logic for learning what can be prefetched and for kicking off
 // speculative prefetching.
 // - The class is a profile keyed service owned by the profile.
 // - All the non-static methods of this class need to be called on the UI
 //   thread.
@@ skipping 61 matching lines @@
     ~PageRequestSummary();
 
     GURL main_frame_url;
     GURL initial_url;
 
     // Stores all subresource requests within a single navigation, from initial
     // main frame request to navigation completion.
     std::vector<URLRequestSummary> subresource_requests;
   };
 
+  // Stores a result of prediction. Essentially, |subresource_urls| is main
+  // result and other fields are used for diagnosis and histograms reporting.
+  struct Prediction {
+    Prediction();
+    Prediction(const Prediction& other);
+    ~Prediction();
+
+    bool is_host;
+    bool is_redirected;
+    std::string main_frame_key;
+    std::vector<GURL> subresource_urls;
+  };
+
+  // Used for reporting redirect prediction success/failure in histograms.
+  // NOTE: This enumeration is used in histograms, so please do not add entries
+  // in the middle.
+  enum class RedirectStatus {
+    NO_REDIRECT,
+    NO_REDIRECT_BUT_PREDICTED,
+    REDIRECT_NOT_PREDICTED,
+    REDIRECT_WRONG_PREDICTED,
+    REDIRECT_CORRECTLY_PREDICTED,
+    MAX
+  };
+
   ResourcePrefetchPredictor(const ResourcePrefetchPredictorConfig& config,
                             Profile* profile);
   ~ResourcePrefetchPredictor() override;
 
   // Starts initialization by posting a task to the DB thread to read the
   // predictor database.
   void StartInitialization();
 
   // Thread safe.
   static bool ShouldRecordRequest(net::URLRequest* request,
@@ skipping 118 matching lines @@
   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.
   void OnNavigationComplete(const NavigationID& nav_id_without_timing_info);
 
   // Returns true iff there is PrefetchData that can be used for a
-  // |main_frame_url| and fills |urls| with resources that need to be
-  // prefetched. |urls| pointer may be equal nullptr to get return value only.
+  // |main_frame_url| and fills |prediction| with resources that need to be
+  // prefetched. |prediction| pointer may be equal nullptr to get return value
+  // only.
   bool GetPrefetchData(const GURL& main_frame_url,
-                       std::vector<GURL>* urls) const;
+                       Prediction* prediction) const;
 
   // Returns true iff the |data_map| contains PrefetchData that can be used
   // for a |main_frame_key| and fills |urls| with resources that need to be
   // prefetched. |urls| pointer may be equal nullptr to get return value only.
   bool PopulatePrefetcherRequest(const std::string& main_frame_key,
                                  const PrefetchDataMap& data_map,
                                  std::vector<GURL>* urls) const;
 
   // Callback for task to read predictor database. Takes ownership of
   // all arguments.
@@ skipping 121 matching lines @@
 
  private:
   ResourcePrefetchPredictor* predictor_;
 
   DISALLOW_COPY_AND_ASSIGN(TestObserver);
 };
 
 }  // namespace predictors
 
 #endif  // CHROME_BROWSER_PREDICTORS_RESOURCE_PREFETCH_PREDICTOR_H_