Remove offscreen compositor contexts.

content/test/web_layer_tree_view_impl_for_testing.cc

Index: content/test/web_layer_tree_view_impl_for_testing.cc
diff --git a/content/test/web_layer_tree_view_impl_for_testing.cc b/content/test/web_layer_tree_view_impl_for_testing.cc
index 8c83e2279f2a526b2562186f0d19898f400915d4..6fcebc61394ec7bc9aaf9a07d9a03470b8106637 100644
--- a/content/test/web_layer_tree_view_impl_for_testing.cc
+++ b/content/test/web_layer_tree_view_impl_for_testing.cc
@@ -150,13 +150,6 @@ WebLayerTreeViewImplForTesting::CreateOutputSurface(bool fallback) {
       new cc::OutputSurface(cc::TestContextProvider::Create()));
 }
 
-scoped_refptr<cc::ContextProvider>
-WebLayerTreeViewImplForTesting::OffscreenContextProvider() {
-  // Unit tests only run in single threaded mode.
-  return content::TestContextProviderFactory::GetInstance()->
-      OffscreenContextProviderForMainThread();
-}
-
 void WebLayerTreeViewImplForTesting::registerViewportLayers(
     const blink::WebLayer* pageScaleLayer,
     const blink::WebLayer* innerViewportScrollLayer,