Add a switch to invert web contents (non-accel only).

content/renderer/render_widget.h

Index: content/renderer/render_widget.h
diff --git a/content/renderer/render_widget.h b/content/renderer/render_widget.h
index c1f53cdbef7c914cf2c5e70ea353ccbd8006cdfd..d1968e0be3fd736e0e32b06c3d903aeeb9b3e060 100644
--- a/content/renderer/render_widget.h
+++ b/content/renderer/render_widget.h
@@ -233,6 +233,7 @@ class CONTENT_EXPORT RenderWidget
   void OnMsgRepaint(const gfx::Size& size_to_paint);
   void OnSetTextDirection(WebKit::WebTextDirection direction);
   void OnGetFPS();
+  void OnInvertWebContent(bool invert);
 
   // Override points to notify derived classes that a paint has happened.
   // WillInitiatePaint happens when we're about to generate a new bitmap and
@@ -495,6 +496,12 @@ class CONTENT_EXPORT RenderWidget
   // case NULL is added to the queue.
   std::deque<ViewHostMsg_UpdateRect*> updates_pending_swap_;
 
+  // Set to true if we should invert all pixels.
+  bool invert_;
+
+  // The Skia paint object for inverting.
+  scoped_ptr<SkPaint> invert_paint_;
+
   DISALLOW_COPY_AND_ASSIGN(RenderWidget);
 };