Fix the crash that could occur when the window is closed while web contents drag is in progress.

content/browser/web_contents/web_contents_view_android.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 "content/browser/web_contents/web_contents_view_android.h"
 
 #include "base/logging.h"
 #include "content/browser/android/content_view_core_impl.h"
 #include "content/browser/renderer_host/render_widget_host_view_android.h"
 #include "content/browser/renderer_host/render_view_host_factory.h"
@@ skipping 112 matching lines @@
 }
 
 void WebContentsViewAndroid::StoreFocus() {
   NOTIMPLEMENTED();
 }
 
 void WebContentsViewAndroid::RestoreFocus() {
   NOTIMPLEMENTED();
 }
 
-bool WebContentsViewAndroid::IsDoingDrag() const {
-  NOTIMPLEMENTED();
-  return false;
-}
-
-void WebContentsViewAndroid::CancelDragAndCloseTab() {
-  NOTIMPLEMENTED();
-}
-
 WebDropData* WebContentsViewAndroid::GetDropData() const {
   NOTIMPLEMENTED();
   return NULL;
 }
 
 bool WebContentsViewAndroid::IsEventTracking() const {
   NOTIMPLEMENTED();
   return false;
 }
 
@@ skipping 55 matching lines @@
 // This is called when we the renderer asks us to take focus back (i.e., it has
 // iterated past the last focusable element on the page).
 void WebContentsViewAndroid::TakeFocus(bool reverse) {
   if (web_contents_->GetDelegate() &&
       web_contents_->GetDelegate()->TakeFocus(web_contents_, reverse))
     return;
   web_contents_->GetRenderWidgetHostView()->Focus();
 }
 
 } // namespace content