Add virtualKeyboardPrivate.onKeyboardClosed API.

ui/keyboard/keyboard_controller.cc

 // Copyright (c) 2013 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/keyboard/keyboard_controller.h"
 
 #include <set>
 
 #include "base/bind.h"
 #include "base/command_line.h"
@@ skipping 170 matching lines @@
 }
 
 KeyboardController::~KeyboardController() {
   if (container_) {
     if (container_->GetRootWindow())
       container_->GetRootWindow()->RemoveObserver(this);
     container_->RemoveObserver(this);
   }
   if (input_method_)
     input_method_->RemoveObserver(this);
+  FOR_EACH_OBSERVER(KeyboardControllerObserver, observer_list_,
+                    OnKeyboardClosed());
   ui_->SetController(nullptr);
 }
 
 // static
 void KeyboardController::ResetInstance(KeyboardController* controller) {
   if (instance_ && instance_ != controller)
     delete instance_;
   instance_ = controller;
 }
 
@@ skipping 281 matching lines @@
   // background during animation.
   NotifyKeyboardBoundsChanging(container_->bounds());
   ui_->EnsureCaretInWorkArea();
 }
 
 void KeyboardController::HideAnimationFinished() {
   ui_->HideKeyboardContainer(container_.get());
 }
 
 }  // namespace keyboard