Port sky_shell to Linux for testing

sky/shell/ui/engine.cc

 // Copyright 2015 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 "sky/shell/ui/engine.h"
 
 #include "base/bind.h"
 #include "base/trace_event/trace_event.h"
 #include "mojo/public/cpp/application/connect.h"
 #include "sky/engine/public/platform/WebInputEvent.h"
@@ skipping 19 matching lines @@
 void ConfigureSettings(blink::WebSettings* settings) {
   settings->setDefaultFixedFontSize(13);
   settings->setDefaultFontSize(16);
   settings->setLoadsImagesAutomatically(true);
 }
 
 PlatformImpl* g_platform_impl = nullptr;
 
 }
 
+Engine::Config::Config() {
+}
+
+Engine::Config::~Config() {
+}
+
 Engine::Engine(const Config& config)
     : config_(config),
       animator_(new Animator(config, this)),
       web_view_(nullptr),
       device_pixel_ratio_(1.0f),
       viewport_observer_binding_(this),
       weak_factory_(this) {
 }
 
 Engine::~Engine() {
@@ skipping 200 matching lines @@
 
 void Engine::DidNavigateLocally(const mojo::String& url) {
 }
 
 void Engine::RequestNavigateHistory(int32_t delta) {
   NOTIMPLEMENTED();
 }
 
 }  // namespace shell
 }  // namespace sky