Validate that ui::Event::time_stamp comes from the same clock as TimeTicks::Now

ui/events/event_utils.cc

Index: ui/events/event_utils.cc
diff --git a/ui/events/event_utils.cc b/ui/events/event_utils.cc
index a079ff22b620093e8673b61d7945ead6a257393b..2e34a82477e0ed6a591b0e325c4a7d1dd34a4a71 100644
--- a/ui/events/event_utils.cc
+++ b/ui/events/event_utils.cc
@@ -61,8 +61,27 @@ int RegisterCustomEventType() {
   return ++g_custom_event_types;
 }
 
-base::TimeTicks EventTimeForNow() {
-  return base::TimeTicks::Now();
+void ValidateEventTimeClock(base::TimeTicks* timestamp) {
+// Restrict this validation to DCHECK builds except when using X11 which is
+// known to provide bogus timestamps that require correction (crbug.com/611950).
+#if defined(USE_X11) || DCHECK_IS_ON()
+  if (base::debug::BeingDebugged())
+    return;
+
+  base::TimeTicks now = EventTimeForNow();
+  int64_t delta = (now - *timestamp).InMilliseconds();
+  if (delta < 0 || delta > 60 * 1000) {
+    UMA_HISTOGRAM_BOOLEAN("Event.TimestampHasValidTimebase", false);
+#if defined(USE_X11)
+    *timestamp = now;
+#else
+    NOTREACHED() << "Unexpected event timestamp, now:" << now
+                 << " event timestamp:" << *timestamp;
+#endif
+  }
+
+  UMA_HISTOGRAM_BOOLEAN("Event.TimestampHasValidTimebase", true);
+#endif
 }
 
 bool ShouldDefaultToNaturalScroll() {