Use a single CGLContextObj to draw and update the IOSurface

content/browser/compositor/io_surface_layer_mac.h

Index: content/browser/compositor/io_surface_layer_mac.h
diff --git a/content/browser/compositor/io_surface_layer_mac.h b/content/browser/compositor/io_surface_layer_mac.h
index 5a218e8f66529e0b94e40ba596d5ea73d3defcfd..a52a75cc95f88a0ff846e13efa2a9cb29a4dc010 100644
--- a/content/browser/compositor/io_surface_layer_mac.h
+++ b/content/browser/compositor/io_surface_layer_mac.h
@@ -16,7 +16,6 @@
 
 namespace content {
 class IOSurfaceTexture;
-class IOSurfaceContext;
 
 // The interface through which the IOSurfaceLayer calls back into
 // the structrue that created it (RenderWidgetHostViewMac or
@@ -117,8 +116,6 @@ class IOSurfaceLayerHelper {
 @interface IOSurfaceLayer : CAOpenGLLayer {
  @private
   scoped_refptr<content::IOSurfaceTexture> iosurface_;
-  scoped_refptr<content::IOSurfaceContext> context_;
-
   scoped_ptr<content::IOSurfaceLayerHelper> helper_;
 }