Revert of Changed Blimp client to start with white screen before drawing contents

blimp/client/feature/compositor/blimp_compositor_unittest.cc

 // 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.
 
 #include "blimp/client/feature/compositor/blimp_compositor.h"
 
 #include "base/thread_task_runner_handle.h"
 #include "blimp/client/feature/compositor/blimp_gpu_memory_buffer_manager.h"
 #include "blimp/common/compositor/blimp_image_serialization_processor.h"
 #include "blimp/common/compositor/blimp_task_graph_runner.h"
@@ skipping 20 matching lines @@
   scoped_refptr<base::SingleThreadTaskRunner> GetCompositorTaskRunner() override
       { return compositor_thread_.task_runner(); }
   cc::TaskGraphRunner* GetTaskGraphRunner() override {
     return &task_graph_runner_; }
   gpu::GpuMemoryBufferManager* GetGpuMemoryBufferManager() override {
     return &gpu_memory_buffer_manager_;
   }
   cc::ImageSerializationProcessor* GetImageSerializationProcessor() override {
     return &image_serialization_processor_;
   }
-  void DidCompleteSwapBuffers() override {}
 
   void SendWebGestureEvent(
       int render_widget_id,
       const blink::WebGestureEvent& gesture_event) override {
     MockableSendWebGestureEvent(render_widget_id);
   }
   void SendCompositorMessage(
       int render_widget_id,
       const cc::proto::CompositorMessage& message) override {
     MockableSendCompositorMessage(render_widget_id);
@@ skipping 119 matching lines @@
               MockableSendCompositorMessage(render_widget_id_)).Times(1);
   EXPECT_CALL(compositor_client_,
               MockableSendWebGestureEvent(render_widget_id_)).Times(1);
 
   compositor_->SendProto(cc::proto::CompositorMessage());
   compositor_->SendGestureEvent(blink::WebGestureEvent());
 }
 
 }  // namespace client
 }  // namespace blimp