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

ui/events/event_utils.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/events/event_utils.h"
 
 #include <vector>
 
 #include "base/metrics/histogram.h"
 #include "ui/display/display.h"
@@ skipping 43 matching lines @@
     default:
       break;
   }
   return event;
 }
 
 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() {
   return GetInternalDisplayTouchSupport() ==
          display::Display::TOUCH_SUPPORT_AVAILABLE;
 }
 
 display::Display::TouchSupport GetInternalDisplayTouchSupport() {
   display::Screen* screen = display::Screen::GetScreen();
   // No screen in some unit tests.
@@ skipping 30 matching lines @@
     case ET_TOUCH_RELEASED:
       UMA_HISTOGRAM_CUSTOM_COUNTS("Event.Latency.OS.TOUCH_RELEASED",
                                   delta.InMicroseconds(), 1, 1000000, 50);
       return;
     default:
       return;
   }
 }
 
 }  // namespace ui