predictors: Collect page load metrics for ResourcePrefetchPredictor.

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 ab2e70b3b1a833ff3fe4fbe4b9b29e94c95e112e..5bfc2bc4d502b698076f17c5160745a061895500 100644
--- a/chrome/browser/predictors/resource_prefetch_predictor.h
+++ b/chrome/browser/predictors/resource_prefetch_predictor.h
@@ -172,6 +172,9 @@ class ResourcePrefetchPredictor
   // in flight.
   void OnPrefetchingFinished(const GURL& main_frame_url);
 
+  // Returns true if prefetching data exists for the |main_frame_url|.
+  virtual bool IsUrlPrefetchable(const GURL& main_frame_url);
+
   // Sets the |observer| to be notified when the resource prefetch predictor
   // data changes. Previously registered observer will be discarded. Call
   // this with nullptr parameter to de-register observer.
@@ -257,15 +260,16 @@ class ResourcePrefetchPredictor
 
   // 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.
-  bool GetPrefetchData(const GURL& main_frame_url, std::vector<GURL>* urls);
+  // prefetched. |urls| pointer may be equal nullptr to get return value only.
+  bool GetPrefetchData(const GURL& main_frame_url,
+                       std::vector<GURL>* urls) 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.
+  // 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);
+                                 std::vector<GURL>* urls) const;
 
   // Callback for task to read predictor database. Takes ownership of
   // all arguments.
@@ -320,11 +324,6 @@ class ResourcePrefetchPredictor
                      size_t max_redirect_map_size,
                      RedirectDataMap* redirect_map);
 
-  // Returns true iff the |data_map| contains PrefetchData that can be used
-  // for |main_frame_key| prefetching.
-  bool IsDataPrefetchable(const std::string& main_frame_key,
-                          const PrefetchDataMap& data_map) const;
-
   // Returns true iff |resource| has sufficient confidence level and required
   // number of hits.
   bool IsResourcePrefetchable(const ResourceData& resource) const;