Simplify ImageDocument checkerboard background styling

third_party/WebKit/Source/core/html/ImageDocument.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2010 Apple 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 400 matching lines @@
       imageStyle.append(AtomicString::number(m_checkerSize));
       imageStyle.append("px;");
 
       int tileSize = m_checkerSize * 2;
       imageStyle.append("background-size: ");
       imageStyle.append(AtomicString::number(tileSize));
       imageStyle.append("px ");
       imageStyle.append(AtomicString::number(tileSize));
       imageStyle.append("px;");
 
+      // Generating the checkerboard pattern this way is not exactly cheap.
+      // If rasterization performance becomes an issue, we could look at using
+      // a cheaper shader (e.g. pre-generate a scaled tile + base64-encode +
+      // inline dataURI => single bitmap shader).
       imageStyle.append(
-          "background-color: white;"
           "background-image:"
           "linear-gradient(45deg, #eee 25%, transparent 25%, transparent 75%, "
           "#eee 75%, #eee 100%),"
-          "linear-gradient(45deg, #eee 25%, transparent 25%, transparent 75%, "
+          "linear-gradient(45deg, #eee 25%, white 25%, white 75%, "
           "#eee 75%, #eee 100%);");
     }
   }
 
   m_imageElement->setAttribute(styleAttr, imageStyle.toAtomicString());
 }
 
 void ImageDocument::imageUpdated() {
   DCHECK(m_imageElement);
 
@@ skipping 150 matching lines @@
 }
 
 bool ImageEventListener::operator==(const EventListener& listener) const {
   if (const ImageEventListener* imageEventListener =
           ImageEventListener::cast(&listener))
     return m_doc == imageEventListener->m_doc;
   return false;
 }
 
 }  // namespace blink