Remove offscreen compositor contexts.

cc/test/layer_tree_test.h

Index: cc/test/layer_tree_test.h
diff --git a/cc/test/layer_tree_test.h b/cc/test/layer_tree_test.h
index 19a379be5ab4b96af5b52cf79bf5fb1a3e430dff..42ef53fff0530dc222690ea2a5c485225a3a7d83 100644
--- a/cc/test/layer_tree_test.h
+++ b/cc/test/layer_tree_test.h
@@ -87,7 +87,6 @@ class TestHooks : public AnimationDelegate {
       Animation::TargetProperty target_property) OVERRIDE {}
 
   virtual scoped_ptr<OutputSurface> CreateOutputSurface(bool fallback) = 0;
-  virtual scoped_refptr<ContextProvider> OffscreenContextProvider() = 0;
 };
 
 class BeginTask;
@@ -186,8 +185,6 @@ class LayerTreeTest : public testing::Test, public TestHooks {
   // Override this for unit tests, which should not produce pixel output.
   virtual scoped_ptr<FakeOutputSurface> CreateFakeOutputSurface(bool fallback);
 
-  virtual scoped_refptr<ContextProvider> OffscreenContextProvider() OVERRIDE;
-
   TestWebGraphicsContext3D* TestContext();