predictors: Mark before_first_contentful_paint for resources fetched before fcp.

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 fa2cfd18367f1742e1cab08e8afa46b2aea35a45..5d3d9b46d937dd9e92a9e38cbed3998094f9c8e4 100644
--- a/chrome/browser/predictors/resource_prefetch_predictor.h
+++ b/chrome/browser/predictors/resource_prefetch_predictor.h
@@ -112,6 +112,7 @@ class ResourcePrefetchPredictor
     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;
@@ -136,6 +137,7 @@ class ResourcePrefetchPredictor
 
     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.
@@ -203,6 +205,8 @@ class ResourcePrefetchPredictor
   // 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);