Ignores mouse motion events when mouse is pressed or drag and drop is in progress

ui/views/corewm/tooltip_controller.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/views/corewm/tooltip_controller.h"
 
 #include <vector>
 
 #include "base/strings/string_util.h"
 #include "base/time/time.h"
@@ skipping 168 matching lines @@
   }
 }
 
 void TooltipController::OnMouseEvent(ui::MouseEvent* event) {
   switch (event->type()) {
     case ui::ET_MOUSE_CAPTURE_CHANGED:
     case ui::ET_MOUSE_EXITED:
     case ui::ET_MOUSE_MOVED:
     case ui::ET_MOUSE_DRAGGED: {
       curr_mouse_loc_ = event->location();
-      aura::Window* target = GetTooltipTarget(*event, &curr_mouse_loc_);
+      aura::Window* target = NULL;
+      // Avoid a call to gfx::Screen::GetWindowAtScreenPoint() since it can be
+      // very expensive on X11 in cases when the tooltip is hidden anyway.
+      if (tooltips_enabled_ &&
+          !aura::Env::GetInstance()->IsMouseButtonDown() &&
+          !IsDragDropInProgress()) {
+        target = GetTooltipTarget(*event, &curr_mouse_loc_);
+      }
       SetTooltipWindow(target);
       if (tooltip_timer_.IsRunning())
         tooltip_timer_.Reset();
 
       if (tooltip_->IsVisible())
         UpdateIfRequired();
       break;
     }
     case ui::ET_MOUSE_PRESSED:
       if ((event->flags() & ui::EF_IS_NON_CLIENT) == 0) {
@@ skipping 144 matching lines @@
     return;
   if (tooltip_window_)
     tooltip_window_->RemoveObserver(this);
   tooltip_window_ = target;
   if (tooltip_window_)
     tooltip_window_->AddObserver(this);
 }
 
 }  // namespace corewm
 }  // namespace views