A mouse event created from the same native event will be marked as repeated.

ui/events/x/events_x_unittest.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 <cstring>
 #include <set>
 
 #include <X11/extensions/XInput2.h>
 #include <X11/Xlib.h>
 #include <X11/Xutil.h>
@@ skipping 190 matching lines @@
   event.xcrossing.y_root = 240;
   EXPECT_EQ(ui::ET_MOUSE_EXITED, ui::EventTypeFromNative(&event));
   EXPECT_EQ("30,40", ui::EventLocationFromNative(&event).ToString());
   EXPECT_EQ("230,240", ui::EventSystemLocationFromNative(&event).ToString());
 }
 
 TEST_F(EventsXTest, ClickCount) {
   XEvent event;
   gfx::Point location(5, 10);
 
+  base::TimeDelta time_stamp = base::TimeDelta::FromMilliseconds(1);
   for (int i = 1; i <= 3; ++i) {
     InitButtonEvent(&event, true, location, 1, 0);
     {
+      event.xbutton.time = time_stamp.InMilliseconds();
       MouseEvent mouseev(&event);
       EXPECT_EQ(ui::ET_MOUSE_PRESSED, mouseev.type());
       EXPECT_EQ(i, mouseev.GetClickCount());
     }
 
     InitButtonEvent(&event, false, location, 1, 0);
     {
+      event.xbutton.time = time_stamp.InMilliseconds();
       MouseEvent mouseev(&event);
       EXPECT_EQ(ui::ET_MOUSE_RELEASED, mouseev.type());
       EXPECT_EQ(i, mouseev.GetClickCount());
     }
+    time_stamp += base::TimeDelta::FromMilliseconds(1);
   }
 }
 
 TEST_F(EventsXTest, TouchEventBasic) {
   std::vector<unsigned int> devices;
   devices.push_back(0);
   ui::SetUpTouchDevicesForTest(devices);
   std::vector<Valuator> valuators;
 
   // Init touch begin with tracking id 5, touch id 0.
@@ skipping 416 matching lines @@
         KeyEventTestApi test_event(&key_event);
         test_event.set_is_char(true);
       }
       EXPECT_FALSE(key_event.flags() & ui::EF_IME_FABRICATED_KEY);
     }
   }
 }
 #endif
 
 }  // namespace ui