Make WebWidget::compositeAndReadbackAsync() return void.

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 1806 matching lines @@
     FrameView* view = page()->mainFrame()->view();
     PaintBehavior oldPaintBehavior = view->paintBehavior();
     view->setPaintBehavior(oldPaintBehavior | PaintBehaviorFlattenCompositingLayers);
 
     PageWidgetDelegate::paint(m_page.get(), pageOverlays(), canvas, rect, isTransparent() ? PageWidgetDelegate::Translucent : PageWidgetDelegate::Opaque);
 
     view->setPaintBehavior(oldPaintBehavior);
 }
 #endif
 
-bool WebViewImpl::compositeAndReadbackAsync(WebCompositeAndReadbackAsyncCallback* callback)
+void WebViewImpl::compositeAndReadbackAsync(WebCompositeAndReadbackAsyncCallback* callback)
 {
-    if (!isAcceleratedCompositingActive())
-        return false;
+    ASSERT(isAcceleratedCompositingActive());
     m_layerTreeView->compositeAndReadbackAsync(callback);
-    return true;
 }
 
 bool WebViewImpl::isTrackingRepaints() const
 {
     if (!page())
         return false;
     FrameView* view = page()->mainFrame()->view();
     return view->isTrackingRepaints();
 }
 
@@ skipping 2264 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