Add/fix some comments for BlimpDelegatingOutputSurface

cc/test/test_delegating_output_surface.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CC_TEST_TEST_DELEGATING_OUTPUT_SURFACE_H_
 #define CC_TEST_TEST_DELEGATING_OUTPUT_SURFACE_H_
 
 #include "base/memory/weak_ptr.h"
 #include "cc/output/output_surface.h"
 #include "cc/output/renderer_settings.h"
@@ skipping 11 matching lines @@
 class TestDelegatingOutputSurfaceClient {
  public:
   virtual ~TestDelegatingOutputSurfaceClient() {}
 
   virtual void DisplayReceivedCompositorFrame(const CompositorFrame& frame) = 0;
   virtual void DisplayWillDrawAndSwap(bool will_draw_and_swap,
                                       const RenderPassList& render_passes) = 0;
   virtual void DisplayDidDrawAndSwap() = 0;
 };
 
+// Delegating output surface that owns and forwards frames to a Display.
 class TestDelegatingOutputSurface : public OutputSurface,
                                     public SurfaceFactoryClient,
                                     public DisplayClient {
  public:
   // Pass true for |force_disable_reclaim_resources| to act like the Display
   // is out-of-process and can't return resources synchronously.
   TestDelegatingOutputSurface(
       scoped_refptr<ContextProvider> compositor_context_provider,
       scoped_refptr<ContextProvider> worker_context_provider,
       std::unique_ptr<OutputSurface> display_output_surface,
@@ skipping 29 matching lines @@
   // DisplayClient implementation.
   void DisplayOutputSurfaceLost() override;
   void DisplaySetMemoryPolicy(const ManagedMemoryPolicy& policy) override;
   void DisplayWillDrawAndSwap(bool will_draw_and_swap,
                               const RenderPassList& render_passes) override;
   void DisplayDidDrawAndSwap() override;
 
  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_;
 
   // Uses surface_manager_.
   std::unique_ptr<SurfaceFactory> surface_factory_;
 
   // Uses surface_manager_.
   std::unique_ptr<Display> display_;
 
   bool bound_ = false;
   TestDelegatingOutputSurfaceClient* test_client_ = nullptr;
 
   std::vector<std::unique_ptr<CopyOutputRequest>> copy_requests_;
 
   base::WeakPtrFactory<TestDelegatingOutputSurface> weak_ptrs_;
 };
 
 }  // namespace cc
 
 #endif  // CC_TEST_TEST_DELEGATING_OUTPUT_SURFACE_H_