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

Index: content/browser/web_contents/web_contents_view_android.cc
diff --git a/content/browser/web_contents/web_contents_view_android.cc b/content/browser/web_contents/web_contents_view_android.cc
index bebc6630f06c7463a482d90d7bfcd248c812c309..d369f01d884efbb08e4f01ddb57834cba0ac4b36 100644
--- a/content/browser/web_contents/web_contents_view_android.cc
+++ b/content/browser/web_contents/web_contents_view_android.cc
@@ -129,15 +129,6 @@ void WebContentsViewAndroid::RestoreFocus() {
   NOTIMPLEMENTED();
 }
 
-bool WebContentsViewAndroid::IsDoingDrag() const {
-  NOTIMPLEMENTED();
-  return false;
-}
-
-void WebContentsViewAndroid::CancelDragAndCloseTab() {
-  NOTIMPLEMENTED();
-}
-
 WebDropData* WebContentsViewAndroid::GetDropData() const {
   NOTIMPLEMENTED();
   return NULL;