Allow the user to drag an extension to the overflow menu, even when its empty

chrome/browser/ui/views/toolbar/extension_toolbar_menu_view.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 "chrome/browser/ui/views/toolbar/extension_toolbar_menu_view.h"
 
 #include "base/bind.h"
 #include "base/message_loop/message_loop.h"
 #include "base/time/time.h"
 #include "chrome/browser/ui/views/frame/browser_view.h"
@@ skipping 26 matching lines @@
       weak_factory_(this) {
   BrowserActionsContainer* main =
       BrowserView::GetBrowserViewForBrowser(browser_)
           ->toolbar()->browser_actions();
   container_ = new BrowserActionsContainer(
       browser_,
       NULL,  // No owner view, means no extra keybindings are registered.
       main);
   container_->Init();
   AddChildView(container_);
+  // We Layout() the container here so that we know the number of actions
+  // that will be visible in ShouldShow().
+  container_->Layout();
 
   // If we were opened for a drop command, we have to wait for the drop to
   // finish so we can close the wrench menu.
   if (wrench_menu_->for_drop()) {
     browser_actions_container_observer_.Add(container_);
     browser_actions_container_observer_.Add(main);
   }
 }
 
 ExtensionToolbarMenuView::~ExtensionToolbarMenuView() {
 }
 
+bool ExtensionToolbarMenuView::ShouldShow() {
+  return wrench_menu_->for_drop() ||
+      container_->VisibleBrowserActionsAfterAnimation();
+}
+
 gfx::Size ExtensionToolbarMenuView::GetPreferredSize() const {
   return container_->GetPreferredSize();
 }
 
 int ExtensionToolbarMenuView::GetHeightForWidth(int width) const {
   const views::MenuConfig& menu_config =
       static_cast<const views::MenuItemView*>(parent())->GetMenuConfig();
   int end_padding = menu_config.arrow_to_edge_padding -
                     BrowserActionsContainer::kItemSpacing;
   width -= start_padding() + end_padding;
@@ skipping 17 matching lines @@
   base::MessageLoop::current()->PostDelayedTask(
       FROM_HERE,
       base::Bind(&ExtensionToolbarMenuView::CloseWrenchMenu,
                  weak_factory_.GetWeakPtr()),
       base::TimeDelta::FromMilliseconds(kCloseMenuDelay));
 }
 
 void ExtensionToolbarMenuView::CloseWrenchMenu() {
   wrench_menu_->CloseMenu();
 }