Fix widget pepper interface crashing after r71544.

Review URL: http://codereview.chromium.org/6368002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@71628 0039d316-1c4b-4281-b951-d872f2087c98

webkit/plugins/ppapi/ppb_widget_impl.cc

@@ -100,7 +100,7 @@ void PPB_Widget_Impl::Invalidate(const PP_Rect* dirty) {
   if (!widget)
     return;
   ScopedResourceId resource(this);
-  widget->Invalidate(instance_->pp_instance(), resource.id, dirty);
+  widget->Invalidate(instance()->pp_instance(), resource.id, dirty);
 }
 
 }  // namespace ppapi

webkit/plugins/ppapi/ppb_widget_impl.h

@@ -39,14 +39,12 @@ class PPB_Widget_Impl : public Resource  {
 
   // Notifies the plugin instance that the given rect needs to be repainted.
   void Invalidate(const PP_Rect* dirty);
-  PluginInstance* instance() { return instance_; }
 
  protected:
   virtual void SetLocationInternal(const PP_Rect* location) = 0;
   PP_Rect location() const { return location_; }
 
  private:
-  scoped_refptr<PluginInstance> instance_;
   PP_Rect location_;
 
   DISALLOW_COPY_AND_ASSIGN(PPB_Widget_Impl);