Remove offscreen compositor contexts.

cc/test/layer_tree_pixel_test.cc

Index: cc/test/layer_tree_pixel_test.cc
diff --git a/cc/test/layer_tree_pixel_test.cc b/cc/test/layer_tree_pixel_test.cc
index a282cc498d6126428afd3c770a6ce5fb65920d76..3237c1af4dc0477e572a8f934112db06adce7f2a 100644
--- a/cc/test/layer_tree_pixel_test.cc
+++ b/cc/test/layer_tree_pixel_test.cc
@@ -64,10 +64,6 @@ scoped_ptr<OutputSurface> LayerTreePixelTest::CreateOutputSurface(
   return output_surface.PassAs<OutputSurface>();
 }
 
-scoped_refptr<ContextProvider> LayerTreePixelTest::OffscreenContextProvider() {
-  return scoped_refptr<ContextProvider>(new TestInProcessContextProvider);
-}
-
 void LayerTreePixelTest::CommitCompleteOnThread(LayerTreeHostImpl* impl) {
   LayerTreeImpl* commit_tree =
       impl->pending_tree() ? impl->pending_tree() : impl->active_tree();