aura: Do not synthesize a mouse-move event during a drag.

ui/aura/window_event_dispatcher.cc

 // Copyright 2014 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/aura/window_event_dispatcher.h"
 
 #include "base/bind.h"
 #include "base/debug/trace_event.h"
 #include "base/logging.h"
 #include "base/message_loop/message_loop.h"
@@ skipping 676 matching lines @@
       window->ContainsPointInRoot(GetLastMouseLocationInRoot())) {
     PostSynthesizeMouseMove();
   }
 }
 
 ui::EventDispatchDetails WindowEventDispatcher::SynthesizeMouseMoveEvent() {
   DispatchDetails details;
   if (!synthesize_mouse_move_)
     return details;
   synthesize_mouse_move_ = false;
+
+  // If one of the mouse buttons is currently down, then do not synthesize a
+  // mouse-move event. In such cases, aura could synthesize a DRAGGED event
+  // instead of a MOVED event, but in multi-display/multi-host scenarios, the
+  // DRAGGED event can be synthesized in the incorrect host. So avoid
+  // synthesizing any events at all.
+  if (Env::GetInstance()->mouse_button_flags())
+    return details;
+
   gfx::Point root_mouse_location = GetLastMouseLocationInRoot();
   if (!window()->bounds().Contains(root_mouse_location))
     return details;
   gfx::Point host_mouse_location = root_mouse_location;
   host_->ConvertPointToHost(&host_mouse_location);
   ui::MouseEvent event(ui::ET_MOUSE_MOVED,
                        host_mouse_location,
                        host_mouse_location,
                        ui::EF_IS_SYNTHESIZED,
                        0);
@@ skipping 147 matching lines @@
       break;
 
     default:
       NOTREACHED();
       break;
   }
   PreDispatchLocatedEvent(target, event);
 }
 
 }  // namespace aura