Adjust interfaces to indicate when tracking is in progress

base/tracked_objects.cc

Index: base/tracked_objects.cc
===================================================================
--- base/tracked_objects.cc	(revision 109040)
+++ base/tracked_objects.cc	(working copy)
@@ -618,6 +618,16 @@
 }
 
 // static
+TrackedTime ThreadData::NowForStartOfRun() {
+  return Now();
+}
+
+// static
+TrackedTime ThreadData::NowForEndOfRun() {
+  return Now();
+}
+
+// static
 TrackedTime ThreadData::Now() {
   if (kTrackAllTaskObjects && tracking_status())
     return TrackedTime::Now();