Stop dispatching mouse move events for wheel scrolling in X11.

ui/events/x/events_x.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_constants.h"
 
 #include <string.h>
 #include <X11/extensions/XInput.h>
 #include <X11/extensions/XInput2.h>
 #include <X11/XKBlib.h>
@@ skipping 424 matching lines @@
           if (GetFlingData(native_event, NULL, NULL, NULL, NULL, &is_cancel))
             return is_cancel ? ET_SCROLL_FLING_CANCEL : ET_SCROLL_FLING_START;
           if (devices->IsScrollEvent(native_event)) {
             return devices->IsTouchpadXInputEvent(native_event) ? ET_SCROLL
                                                                 : ET_MOUSEWHEEL;
           }
           if (devices->IsCMTMetricsEvent(native_event))
             return ET_UMA_DATA;
           if (GetButtonMaskForX2Event(xievent))
             return ET_MOUSE_DRAGGED;
+          if (DeviceDataManagerX11::GetInstance()->HasEventData(
+                  xievent, DeviceDataManagerX11::DT_CMT_SCROLL_X) ||
+              DeviceDataManagerX11::GetInstance()->HasEventData(
+                  xievent, DeviceDataManagerX11::DT_CMT_SCROLL_Y)) {
+            // Don't produce mouse move events for mousewheel scrolls.
+            return ET_UNKNOWN;
+          }
+
           return ET_MOUSE_MOVED;
         }
         case XI_KeyPress:
           return ET_KEY_PRESSED;
         case XI_KeyRelease:
           return ET_KEY_RELEASED;
       }
     }
     default:
       break;
@@ skipping 445 matching lines @@
       xievent->detail =
           UpdateX11EventButton(event->changed_button_flags(), xievent->detail);
       break;
     }
     default:
       break;
   }
 }
 
 }  // namespace ui