Add/fix some comments for BlimpDelegatingOutputSurface

cc/test/test_delegating_output_surface.h

Index: cc/test/test_delegating_output_surface.h
diff --git a/cc/test/test_delegating_output_surface.h b/cc/test/test_delegating_output_surface.h
index f5ac2944d91690340fdef84def374803b3c06e12..fc5f1f81ae464ae8b33dddeca070c834509942a9 100644
--- a/cc/test/test_delegating_output_surface.h
+++ b/cc/test/test_delegating_output_surface.h
@@ -29,6 +29,7 @@ class TestDelegatingOutputSurfaceClient {
   virtual void DisplayDidDrawAndSwap() = 0;
 };
 
+// Delegating output surface that owns and forwards frames to a Display.
 class TestDelegatingOutputSurface : public OutputSurface,
                                     public SurfaceFactoryClient,
                                     public DisplayClient {
@@ -78,8 +79,8 @@ class TestDelegatingOutputSurface : public OutputSurface,
  private:
   void DidDrawCallback(bool synchronous);
 
-  // TODO(danakj): These don't to be stored in unique_ptrs when OutputSurface
-  // is owned/destroyed on the compositor thread.
+  // TODO(danakj): These don't need to be stored in unique_ptrs when
+  // OutputSurface is owned/destroyed on the compositor thread.
   std::unique_ptr<SurfaceManager> surface_manager_;
   std::unique_ptr<SurfaceIdAllocator> surface_id_allocator_;
   SurfaceId delegated_surface_id_;