predictors: Several improvements for redirects database.

chrome/browser/predictors/resource_prefetch_predictor.h

Index: chrome/browser/predictors/resource_prefetch_predictor.h
diff --git a/chrome/browser/predictors/resource_prefetch_predictor.h b/chrome/browser/predictors/resource_prefetch_predictor.h
index cec2207d48f5d4d8e62642162e41a75cbbbdb7e7..4c2e45910c6902d63b5e8101f81317f0777f3ba8 100644
--- a/chrome/browser/predictors/resource_prefetch_predictor.h
+++ b/chrome/browser/predictors/resource_prefetch_predictor.h
@@ -298,12 +298,6 @@ class ResourcePrefetchPredictor
   // Returns true if the request (should have a response in it) is "no-store".
   static bool IsNoStore(const net::URLRequest* request);
 
-  // Returns true iff |redirect_data_map| contains confident redirect endpoint
-  // for |entry_point| and assigns it to the |redirect_endpoint|.
-  static bool GetRedirectEndpoint(const std::string& entry_point,
-                                  const RedirectDataMap& redirect_data_map,
-                                  std::string* redirect_endpoint);
-
   static void SetAllowPortInUrlsForTesting(bool state);
 
   // KeyedService methods override.
@@ -321,6 +315,16 @@ class ResourcePrefetchPredictor
   // this point are the only ones considered for prefetching.
   void OnNavigationComplete(const NavigationID& nav_id_without_timing_info);
 
+  // Returns true iff one of the following conditions is true
+  // * |redirect_data_map| contains confident redirect endpoint for
+  //   |entry_point| and assigns it to the |redirect_endpoint|
+  //
+  // * |redirect_data_map| doens't contain an entry for |entry_point| and
+  //   assings |entry_point| to the |redirect_endpoint|.
+  bool GetRedirectEndpoint(const std::string& entry_point,

[Benoit L, 2017/04/10 09:50:35]

Can you add (in the implementation, not the .h) a comment explaining why the
heuristics are set this way?
It's not entirely clear without context, so let's be nice with future-us, or
with the poor soul who will look at this code in the future.

[alexilin, 2017/04/10 17:43:25]

Done.

+                           const RedirectDataMap& redirect_data_map,
+                           std::string* redirect_endpoint) const;
+
   // Returns true iff there is PrefetchData that can be used for a
   // |main_frame_url| and fills |prediction| with resources that need to be
   // prefetched. |prediction| pointer may be equal nullptr to get return value