(not for commit) Create 2nd ContextProvider for Ganesh rasterization.

cc/test/pixel_test_output_surface.cc

Index: cc/test/pixel_test_output_surface.cc
diff --git a/cc/test/pixel_test_output_surface.cc b/cc/test/pixel_test_output_surface.cc
index ced1898e4db34468c9d49a522aa14c0a2c8d23c1..2825d316d4013534ef934dc95e3a4b307ce23e37 100644
--- a/cc/test/pixel_test_output_surface.cc
+++ b/cc/test/pixel_test_output_surface.cc
@@ -11,8 +11,10 @@ namespace cc {
 
 PixelTestOutputSurface::PixelTestOutputSurface(
     scoped_refptr<ContextProvider> context_provider,
+    scoped_refptr<ContextProvider> worker_context_provider,
     bool flipped_output_surface)
-    : OutputSurface(context_provider), external_stencil_test_(false) {
+    : OutputSurface(context_provider, worker_context_provider),
+      external_stencil_test_(false) {
   capabilities_.flipped_output_surface = flipped_output_surface;
 }