Free temporary GPU and memory resources held by inactive or hidden 2D canvases

Source/web/WebViewImpl.cpp

 /*
  * Copyright (C) 2011, 2012 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 3908 matching lines @@
 }
 
 void WebViewImpl::setVisibilityState(WebPageVisibilityState visibilityState,
                                      bool isInitialState) {
     if (!page())
         return;
 
     ASSERT(visibilityState == WebPageVisibilityStateVisible || visibilityState == WebPageVisibilityStateHidden || visibilityState == WebPageVisibilityStatePrerender);
     m_page->setVisibilityState(static_cast<PageVisibilityState>(static_cast<int>(visibilityState)), isInitialState);
 
+    bool visible = visibilityState == WebPageVisibilityStateVisible;

[Stephen White, 2014/01/24 18:52:35]

Don't see the need for this change; maybe a remnant of an older version (or I'm
being dumb).

     if (m_layerTreeView) {
-        bool visible = visibilityState == WebPageVisibilityStateVisible;
         m_layerTreeView->setVisible(visible);
     }
 }
 
 bool WebViewImpl::requestPointerLock()
 {
     return m_client && m_client->requestPointerLock();
 }
 
 void WebViewImpl::requestPointerUnlock()
@@ skipping 45 matching lines @@
     const PageScaleConstraints& constraints = m_pageScaleConstraintsSet.pageDefinedConstraints();
 
     if (!mainFrameImpl() || !mainFrameImpl()->frameView())
         return false;
 
     return mainFrameImpl()->frameView()->layoutSize().width() == m_size.width
         || (constraints.minimumScale == constraints.maximumScale && constraints.minimumScale != -1);
 }
 
 } // namespace blink