Handle XI_Enter and XI_Leave events.

ui/events/x/events_x_utils.cc

 // Copyright (c) 2016 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/x/events_x_utils.h"
 
 #include <stddef.h>
 #include <string.h>
 #include <X11/extensions/XInput.h>
 #include <X11/extensions/XInput2.h>
@@ skipping 252 matching lines @@
       return ui::ET_TOUCH_RELEASED;
     case XI_Motion:
       // Should not convert any emulated Motion event from touch device to
       // touch event.
       if (!(event->flags & XIPointerEmulated) && GetButtonMaskForX2Event(event))
         return ui::ET_TOUCH_MOVED;
       return ui::ET_UNKNOWN;
     case XI_DeviceChanged:
       // This can happen when --touch-devices flag is used.
       return ui::ET_UNKNOWN;
+    case XI_Leave:
+    case XI_Enter:
+      // We don't handle enter/leave but they're expected.

[sadrul, 2016/09/01 23:12:55]

We do handle these events though:
https://cs.chromium.org/chromium/src/ui/views/widget/desktop_aura/desktop_win...

I think we need to return after processing
XI_Leave/XI_Enter/XI_FocusIn/XI_FocusOut events in that function, in addition to
the change in this function. But include FocusIn/FocusOut here, and update the
comment?

[kylechar, 2016/09/06 17:29:57]

Done.

+      return ui::ET_UNKNOWN;
     default:
       NOTREACHED();
   }
   return ui::ET_UNKNOWN;
 }
 
 double GetTouchParamFromXEvent(const XEvent& xev,
                                ui::DeviceDataManagerX11::DataType val,
                                double default_value) {
   ui::DeviceDataManagerX11::GetInstance()->GetEventData(xev, val,
@@ skipping 517 matching lines @@
 }
 
 void ResetTimestampRolloverCountersForTesting(
     std::unique_ptr<base::TickClock> tick_clock) {
   g_last_seen_timestamp_ms = 0;
   g_rollover_ms = 0;
   SetEventTickClockForTesting(std::move(tick_clock));
 }
 
 }  // namespace ui