Optional <TimeDelta> since they may be non existent.

components/page_load_metrics/browser/page_load_metrics_observer.h

Index: components/page_load_metrics/browser/page_load_metrics_observer.h
diff --git a/components/page_load_metrics/browser/page_load_metrics_observer.h b/components/page_load_metrics/browser/page_load_metrics_observer.h
index c42f36d93ee467eab1375a7bad8abbb8b90a4441..8613dc796d74889581e9bf0b3fdccba006ad993d 100644
--- a/components/page_load_metrics/browser/page_load_metrics_observer.h
+++ b/components/page_load_metrics/browser/page_load_metrics_observer.h
@@ -6,6 +6,7 @@
 #define COMPONENTS_PAGE_LOAD_METRICS_BROWSER_PAGE_LOAD_METRICS_OBSERVER_H_
 
 #include "base/macros.h"
+#include "base/optional.h"
 #include "components/page_load_metrics/common/page_load_timing.h"
 #include "content/public/browser/navigation_handle.h"
 #include "url/gurl.h"
@@ -51,21 +52,21 @@ enum UserAbortType {
 };
 
 struct PageLoadExtraInfo {
-  PageLoadExtraInfo(base::TimeDelta first_background_time,
-                    base::TimeDelta first_foreground_time,
+  PageLoadExtraInfo(base::Optional<base::TimeDelta> first_background_time,

[Bryan McQuade, 2016/03/29 18:33:43]

given that base::Optional is bigger than a pointer here (bool+double), should we
pass it by const reference rather than by value?

[shivanisha, 2016/03/29 18:54:24]

Makes sense. will do

+                    base::Optional<base::TimeDelta> first_foreground_time,
                     bool started_in_foreground,
                     const GURL& committed_url,
-                    base::TimeDelta time_to_commit,
+                    base::Optional<base::TimeDelta> time_to_commit,
                     UserAbortType abort_type,
-                    base::TimeDelta time_to_abort);
+                    base::Optional<base::TimeDelta> time_to_abort);
+
+  ~PageLoadExtraInfo();
 
   // The first time that the page was backgrounded since the navigation started.
-  // If the page has not been backgrounded this will be base::TimeDelta().
-  const base::TimeDelta first_background_time;
+  const base::Optional<base::TimeDelta> first_background_time;
 
   // The first time that the page was foregrounded since the navigation started.
-  // If the page has not been foregrounded this will be base::TimeDelta().
-  const base::TimeDelta first_foreground_time;
+  const base::Optional<base::TimeDelta> first_foreground_time;
 
   // True if the page load started in the foreground.
   const bool started_in_foreground;
@@ -74,15 +75,13 @@ struct PageLoadExtraInfo {
   // empty.
   const GURL committed_url;
 
-  // Time from navigation start until commit. If the page load did not commit,
-  // |time_to_commit| will be zero.
-  const base::TimeDelta time_to_commit;
+  // Time from navigation start until commit.
+  const base::Optional<base::TimeDelta> time_to_commit;
 
   // The abort time and time to abort for this page load. If the page was not
-  // aborted, |abort_type| will be |ABORT_NONE| and |time_to_abort| will be
-  // |base::TimeDelta()|.
+  // aborted, |abort_type| will be |ABORT_NONE|
   const UserAbortType abort_type;
-  const base::TimeDelta time_to_abort;
+  const base::Optional<base::TimeDelta> time_to_abort;
 };
 
 // Interface for PageLoadMetrics observers. All instances of this class are