predictors: Mark before_first_contentful_paint for resources fetched before fcp.

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 94 matching lines @@
   // Stores the data that we need to get from the URLRequest.
   struct URLRequestSummary {
     URLRequestSummary();
     URLRequestSummary(const URLRequestSummary& other);
     ~URLRequestSummary();
 
     NavigationID navigation_id;
     GURL resource_url;
     content::ResourceType resource_type;
     net::RequestPriority priority;
+    bool before_first_contentful_paint;

[alexilin, 2017/03/17 14:46:46]

You need to initialize this field in URLRequestSummary constructors.

[trevordixon, 2017/03/27 12:30:08]

Done.

 
     // Only for responses.
     std::string mime_type;
     bool was_cached;
     GURL redirect_url;  // Empty unless request was redirected to a valid url.
 
     bool has_validators;
     bool always_revalidate;
 
     // Initializes a |URLRequestSummary| from a |URLRequest| response.
     // Returns true for success. Note: NavigationID is NOT initialized
     // by this function.
     static bool SummarizeResponse(const net::URLRequest& request,
                                   URLRequestSummary* summary);
   };
 
   // Stores the data learned from a single navigation.
   struct PageRequestSummary {
     explicit PageRequestSummary(const GURL& main_frame_url);
     PageRequestSummary(const PageRequestSummary& other);
     ~PageRequestSummary();
 
     GURL main_frame_url;
     GURL initial_url;
+    base::TimeDelta first_contentful_paint_time;

[alexilin, 2017/03/17 14:46:46]

Unused field.

[trevordixon, 2017/03/27 12:30:08]

Oops.

 
     // 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();
@@ skipping 47 matching lines @@
   // 'ResourcePrefetchPredictorObserver' calls the below functions to inform the
   // predictor of main frame and resource requests. Should only be called if the
   // corresponding Should* functions return true.
   void RecordURLRequest(const URLRequestSummary& request);
   void RecordURLResponse(const URLRequestSummary& response);
   void RecordURLRedirect(const URLRequestSummary& response);
 
   // Called when the main frame of a page completes loading.
   void RecordMainFrameLoadComplete(const NavigationID& navigation_id);
 
+  void RecordFirstContentfulPaint(const NavigationID navigation_id);

[alexilin, 2017/03/17 14:46:46]

Please, add a comment to this function.

[trevordixon, 2017/03/27 12:30:08]

Done.

+
   // Starts prefetching if it is enabled for |origin| and prefetching data
   // exists for the |main_frame_url| either at the URL or at the host level.
   void StartPrefetching(const GURL& main_frame_url, PrefetchOrigin origin);
 
   // Stops prefetching that may be in progress corresponding to
   // |main_frame_url|.
   void StopPrefetching(const GURL& main_frame_url);
 
   // Called when ResourcePrefetcher is finished, i.e. there is nothing pending
   // in flight.
@@ skipping 235 matching lines @@
 
  private:
   ResourcePrefetchPredictor* predictor_;
 
   DISALLOW_COPY_AND_ASSIGN(TestObserver);
 };
 
 }  // namespace predictors
 
 #endif  // CHROME_BROWSER_PREDICTORS_RESOURCE_PREFETCH_PREDICTOR_H_