Fix the bug of multiple overlays.

ash/keyboard_overlay/keyboard_overlay_view.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/keyboard_overlay/keyboard_overlay_view.h"
 
 #include "ash/keyboard_overlay/keyboard_overlay_delegate.h"
 #include "ash/shell.h"
 #include "base/strings/utf_string_conversions.h"
 #include "content/public/browser/browser_context.h"
@@ skipping 25 matching lines @@
     content::BrowserContext* context,
     WebDialogDelegate* delegate,
     WebContentsHandler* handler)
     : views::WebDialogView(context, delegate, handler) {
 }
 
 KeyboardOverlayView::~KeyboardOverlayView() {
 }
 
 void KeyboardOverlayView::Cancel() {
-  Shell::GetInstance()->overlay_filter()->Deactivate();
+  Shell::GetInstance()->overlay_filter()->Deactivate(this);
   views::Widget* widget = GetWidget();
   if (widget)
     widget->Close();
 }
 
 bool KeyboardOverlayView::IsCancelingKeyEvent(ui::KeyEvent* event) {
   if (event->type() != ui::ET_KEY_PRESSED)
     return false;
   // Ignore the caps lock state.
   const int flags = (event->flags() & ~ui::EF_CAPS_LOCK_DOWN);
   for (size_t i = 0; i < arraysize(kCancelKeys); ++i) {
     if ((kCancelKeys[i].key_code == event->key_code()) &&
         (kCancelKeys[i].flags == flags))
       return true;
   }
   return false;
 }
 
 aura::Window* KeyboardOverlayView::GetWindow() {
   return GetWidget()->GetNativeWindow();
 }
 
+// static
 void KeyboardOverlayView::ShowDialog(
     content::BrowserContext* context,
     WebContentsHandler* handler,
     const GURL& url) {
+  if (Shell::GetInstance()->overlay_filter()->IsActive())
+    return;
+
   KeyboardOverlayDelegate* delegate = new KeyboardOverlayDelegate(
       l10n_util::GetStringUTF16(IDS_ASH_KEYBOARD_OVERLAY_TITLE), url);
   KeyboardOverlayView* view =
       new KeyboardOverlayView(context, delegate, handler);
   delegate->Show(view);
 
   Shell::GetInstance()->overlay_filter()->Activate(view);
 }
 
 void KeyboardOverlayView::WindowClosing() {
   Cancel();
 }
 
 // static
 void KeyboardOverlayView::GetCancelingKeysForTesting(
     std::vector<KeyboardOverlayView::KeyEventData>* canceling_keys) {
   CHECK(canceling_keys);
   canceling_keys->clear();
   for (size_t i = 0; i < arraysize(kCancelKeys); ++i)
     canceling_keys->push_back(kCancelKeys[i]);
 }
 
 }  // namespace ash