Turn MoveLeave event sending into a feature for testing enabling it.

ui/events/blink/web_input_event.cc

 // Copyright 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/blink/web_input_event.h"
 
 #include "ui/events/base_event_utils.h"
 #include "ui/events/blink/blink_event_util.h"
+#include "ui/events/blink/blink_features.h"
 #include "ui/events/event.h"
 #include "ui/events/event_utils.h"
 #include "ui/events/keycodes/dom/keycode_converter.h"
 #include "ui/events/keycodes/keyboard_code_conversion.h"
 
 #if defined(OS_WIN)
 #include "ui/events/blink/web_input_event_builders_win.h"
 #endif
 
 namespace ui {
@@ skipping 359 matching lines @@
   int click_count = 0;
   switch (event.type()) {
     case ET_MOUSE_PRESSED:
       type = blink::WebInputEvent::MouseDown;
       click_count = event.GetClickCount();
       break;
     case ET_MOUSE_RELEASED:
       type = blink::WebInputEvent::MouseUp;
       click_count = event.GetClickCount();
       break;
-    case ET_MOUSE_EXITED:
-// TODO(chaopeng) this fix only for chromeos now, should convert ET_MOUSE_EXITED
-// to MouseLeave when crbug.com/450631 fixed.
-#if defined(OS_CHROMEOS)
-      type = blink::WebInputEvent::MouseLeave;
+    case ET_MOUSE_EXITED: {
+      static bool s_send_leave =
+          base::FeatureList::IsEnabled(features::kSendMouseLeaveEvents);
+      type = s_send_leave ? blink::WebInputEvent::MouseLeave
+                          : blink::WebInputEvent::MouseMove;
       break;
-#endif
+    }
     case ET_MOUSE_ENTERED:
     case ET_MOUSE_MOVED:
     case ET_MOUSE_DRAGGED:
       type = blink::WebInputEvent::MouseMove;
       break;
     default:
       NOTIMPLEMENTED() << "Received unexpected event: " << event.type();
       break;
   }
 
@@ skipping 44 matching lines @@
   webkit_event.tiltX = roundf(event.pointer_details().tilt_x);
   webkit_event.tiltY = roundf(event.pointer_details().tilt_y);
   webkit_event.force = event.pointer_details().force;
   webkit_event.pointerType =
       EventPointerTypeToWebPointerType(event.pointer_details().pointer_type);
 
   return webkit_event;
 }
 
 }  // namespace ui