Revert of cancel overlay-scrollbar hover state when moving pointer out of window for ChromeOS

ui/events/blink/input_handler_proxy.cc

 // Copyright 2013 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/input_handler_proxy.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 
@@ skipping 387 matching lines @@
     }
     case WebInputEvent::MouseMove: {
       const WebMouseEvent& mouse_event =
           static_cast<const WebMouseEvent&>(event);
       // TODO(davemoore): This should never happen, but bug #326635 showed some
       // surprising crashes.
       CHECK(input_handler_);
       input_handler_->MouseMoveAt(gfx::Point(mouse_event.x, mouse_event.y));
       return DID_NOT_HANDLE;
     }
-    case WebInputEvent::MouseLeave: {
-      CHECK(input_handler_);
-      input_handler_->MouseLeave();
-      return DID_NOT_HANDLE;
-    }
 
     default:
       if (WebInputEvent::isKeyboardEventType(event.type)) {
         // Only call |CancelCurrentFling()| if a fling was active, as it will
         // otherwise disrupt an in-progress touch scroll.
         if (fling_curve_)
           CancelCurrentFling();
       }
       break;
   }
@@ skipping 973 matching lines @@
   // is made asynchronously, to minimize divergence between main thread and
   // impl thread event handling paths.
   base::ThreadTaskRunnerHandle::Get()->PostTask(
       FROM_HERE,
       base::Bind(&InputScrollElasticityController::ObserveGestureEventAndResult,
                  scroll_elasticity_controller_->GetWeakPtr(), gesture_event,
                  scroll_result));
 }
 
 }  // namespace ui