Periodically remove old pending navigation entries.

chrome/browser/data_use_measurement/chrome_data_use_ascriber.h

Index: chrome/browser/data_use_measurement/chrome_data_use_ascriber.h
diff --git a/chrome/browser/data_use_measurement/chrome_data_use_ascriber.h b/chrome/browser/data_use_measurement/chrome_data_use_ascriber.h
index dc83994b98f6987136226ec822b87620f0dda521..03121181f8ee74805ddda9b91a081eb58f9b99c4 100644
--- a/chrome/browser/data_use_measurement/chrome_data_use_ascriber.h
+++ b/chrome/browser/data_use_measurement/chrome_data_use_ascriber.h
@@ -99,6 +99,8 @@ class ChromeDataUseAscriber : public DataUseAscriber {
                                       void* navigation_handle);
 
  private:
+  friend class ChromeDataUseAscriberTest;
+
   // Use as a key in the render frame map. Corresponds to a unique
   // RenderFrameHost.
   typedef std::pair<int, int> RenderFrameHostID;
@@ -131,6 +133,13 @@ class ChromeDataUseAscriber : public DataUseAscriber {
 
   void DeletePendingNavigationEntry(content::GlobalRequestID global_request_id);
 
+  // The ReadyToCommitNavigation() callback is used to remove entries from
+  // |pending_navigation_data_use_map_|. However, there are a number of race
+  // conditions which make this callback unreliable until PlzNavigate is used.
+  // Until then, this method periodically deletes old navigation entries
+  // that have finished data use.
+  void DeleteOldPendingNavigationEntries(base::Time now);
+
   // Owner for all instances of DataUseRecorder. An instance is kept in this
   // list if any entity (render frame hosts, URLRequests, pending navigations)
   // that ascribe data use to the instance exists, and deleted when all
@@ -149,6 +158,8 @@ class ChromeDataUseAscriber : public DataUseAscriber {
                      GlobalRequestIDHash>
       pending_navigation_data_use_map_;
 
+  base::Time last_pending_navigations_discard_time_;
+
   DISALLOW_COPY_AND_ASSIGN(ChromeDataUseAscriber);
 };