Prevents double-clicks on a tab close button from aslo maximizing the browser

ash/wm/toplevel_window_event_handler.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 "ash/wm/toplevel_window_event_handler.h"
 
 #include "ash/shell.h"
 #include "ash/wm/resize_shadow_controller.h"
 #include "ash/wm/window_resizer.h"
 #include "ash/wm/window_state.h"
@@ skipping 458 matching lines @@
   // mouse-drag-release-press case, where the mouse is released and
   // pressed without mouse move event.
   int component = GetWindowComponent(target, *event);
   if ((event->flags() &
         (ui::EF_IS_DOUBLE_CLICK | ui::EF_IS_TRIPLE_CLICK)) == 0 &&
       WindowResizer::GetBoundsChangeForWindowComponent(component)) {
     gfx::Point location_in_parent(
         ConvertPointToParent(target, event->location()));
     AttemptToStartDrag(target, location_in_parent, component,
                        aura::client::WINDOW_MOVE_SOURCE_MOUSE);
-    event->StopPropagation();
+    // Set as handled so that other event handlers do no act upon the event
+    // but still receive it so that they receive both parts of each pressed/
+    // released pair.
+    event->SetHandled();
   } else {
     CompleteDrag(DRAG_COMPLETE);
   }
 }
 
 void ToplevelWindowEventHandler::HandleMouseReleased(
     aura::Window* target,
     ui::MouseEvent* event) {
   if (event->phase() != ui::EP_PRETARGET)
     return;
 
   CompleteDrag(event->type() == ui::ET_MOUSE_RELEASED ?
                    DRAG_COMPLETE : DRAG_REVERT);
   // Completing the drag may result in hiding the window. If this happens
-  // return true so no other handlers/observers see the event. Otherwise
-  // they see the event on a hidden window.
+  // mark the event as handled so no other handlers/observers act upon the
+  // event. They should see the event on a hidden window, to determine targets
+  // of destructive actions such as hiding. They should not act upon them.
   if (window_resizer_ &&
       event->type() == ui::ET_MOUSE_CAPTURE_CHANGED &&
       !target->IsVisible()) {
-    event->StopPropagation();
+    event->SetHandled();
   }
 }
 
 void ToplevelWindowEventHandler::HandleDrag(
     aura::Window* target,
     ui::LocatedEvent* event) {
   // This function only be triggered to move window
   // by mouse drag or touch move event.
   DCHECK(event->type() == ui::ET_MOUSE_DRAGGED ||
          event->type() == ui::ET_TOUCH_MOVED ||
@@ skipping 92 matching lines @@
 
 void ToplevelWindowEventHandler::ResizerWindowDestroyed() {
   // We explicitly don't invoke RevertDrag() since that may do things to window.
   // Instead we destroy the resizer.
   window_resizer_.reset();
 
   CompleteDrag(DRAG_REVERT);
 }
 
 }  // namespace ash