Remove the forceCompositingMode setting.

Source/web/WebPopupMenuImpl.cpp

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 188 matching lines @@
 void WebPopupMenuImpl::animate(double)
 {
 }
 
 void WebPopupMenuImpl::layout()
 {
 }
 
 void WebPopupMenuImpl::enterForceCompositingMode(bool enter)
 {
+    // FIXME: Is this function really correct? The other overrides of this function
+    // just used to set forceCompositingMode before we removed that setting.
+    // crbug.com/378029
     if (m_isAcceleratedCompositingActive == enter)
         return;
 
     if (!enter) {
         m_isAcceleratedCompositingActive = false;
         m_client->didDeactivateCompositor();
     } else if (m_layerTreeView) {
         m_isAcceleratedCompositingActive = true;
         m_client->didActivateCompositor();
     } else {
@@ skipping 222 matching lines @@
     ASSERT(widget == m_widget);
     if (m_widget) {
         m_widget->setClient(0);
         m_widget = 0;
     }
     if (m_client)
         m_client->closeWidgetSoon();
 }
 
 } // namespace blink