Let ChromiumBridge::paintTextField check if the Color object passed in is valid or not.

webkit/api/src/ChromiumBridge.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 293 matching lines @@
     webKitClient()->themeEngine()->paintScrollbarTrack(
         gc->platformContext()->canvas(), part, state, classicState, rect,
         alignRect);
 }
 
 void ChromiumBridge::paintTextField(
     GraphicsContext* gc, int part, int state, int classicState,
     const IntRect& rect, const Color& color, bool fillContentArea,
     bool drawEdges)
 {
+    // Fallback to white when |color| is invalid.
+    RGBA32 backgroundColor = color.isValid() ? color.rgb() : Color::white;
+
     webKitClient()->themeEngine()->paintTextField(
         gc->platformContext()->canvas(), part, state, classicState, rect,
-        color.rgb(), fillContentArea, drawEdges);
+        backgroundColor, fillContentArea, drawEdges);
 }
 
 void ChromiumBridge::paintTrackbar(
     GraphicsContext* gc, int part, int state, int classicState,
     const IntRect& rect)
 {
     webKitClient()->themeEngine()->paintTrackbar(
         gc->platformContext()->canvas(), part, state, classicState, rect);
 }
 
@@ skipping 56 matching lines @@
 
     return webKitClient()->visitedLinkHash(buffer.data(), buffer.length());
 }
 
 bool ChromiumBridge::isLinkVisited(WebCore::LinkHash visitedLinkHash)
 {
     return webKitClient()->isLinkVisited(visitedLinkHash);
 }
 
 } // namespace WebCore