Move new Startup.FirstWebContents.* stats to Startup.FirstWebContents.*2.

components/startup_metric_utils/startup_metric_utils.h

Index: components/startup_metric_utils/startup_metric_utils.h
diff --git a/components/startup_metric_utils/startup_metric_utils.h b/components/startup_metric_utils/startup_metric_utils.h
index d5b0e8fa19d226042a591ee12efa41d8c5041102..684046cb435a2305d48f6195fc19f3a3a0d3f095 100644
--- a/components/startup_metric_utils/startup_metric_utils.h
+++ b/components/startup_metric_utils/startup_metric_utils.h
@@ -68,12 +68,22 @@ void RecordBrowserWindowDisplay(const base::Time& time);
 // Call this with the time delta that the browser spent opening its tabs.
 void RecordBrowserOpenTabsDelta(const base::TimeDelta& delta);
 
-// Call this with the time when the first web contents loaded its main frame.
+// Call this with the time when the first web contents loaded its main frame,
+// only if the first web contents was unimpended in its attempt to do so.
 void RecordFirstWebContentsMainFrameLoad(const base::Time& time);
 
-// Call this with the time when the first web contents had a non-empty paint.
+// Call this with the time when the first web contents loaded its main frame.
+// This records an old stat kept for comparison purposes until M49.
+void RecordDeprecatedFirstWebContentsMainFrameLoad(const base::Time& time);
+
+// Call this with the time when the first web contents had a non-empty paint,
+// only if the first web contents was unimpended in its attempt to do so.
 void RecordFirstWebContentsNonEmptyPaint(const base::Time& time);
 
+// Call this with the time when the first web contents had a non-empty paint.
+// This records an old stat kept for comparison purposes until M49.
+void RecordDeprecatedFirstWebContentsNonEmptyPaint(const base::Time& time);
+
 // Call this with the time when the first web contents began navigating its main
 // frame.
 void RecordFirstWebContentsMainNavigationStart(const base::Time& time);