Make WebView::close not crash and start to fix navigation in SkyShell

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 "mojo/public/cpp/application/connect.h"
 #include "sky/engine/public/platform/WebInputEvent.h"
 #include "sky/engine/public/web/Sky.h"
@@ skipping 101 matching lines @@
 
 void Engine::OnInputEvent(InputEventPtr event) {
   scoped_ptr<blink::WebInputEvent> web_event =
       ConvertEvent(event, device_pixel_ratio_);
   if (!web_event)
     return;
   web_view_->handleInputEvent(*web_event);
 }
 
 void Engine::LoadURL(const mojo::String& url) {
-  web_view_ = blink::WebView::create(this);
+  // Something bad happens if you try to call WebView::close and replace
+  // the webview.  So for now we just load into the existing one. :/
+  if (!web_view_)
+    web_view_ = blink::WebView::create(this);
   ConfigureSettings(web_view_->settings());
   web_view_->setMainFrame(blink::WebLocalFrame::create(this));
   UpdateWebViewSize();
   web_view_->mainFrame()->load(GURL(url));
 }
 
+void Engine::frameDetached(blink::WebFrame* frame) {
+  // |frame| is invalid after here.
+  frame->close();
+}
+
 void Engine::initializeLayerTreeView() {
 }
 
 void Engine::scheduleVisualUpdate() {
   animator_->RequestFrame();
 }
 
+blink::ServiceProvider* Engine::services() {
+  return this;
+}
+
+mojo::NavigatorHost* Engine::NavigatorHost() {
+  return this;
+}
+
+void Engine::RequestNavigate(mojo::Target target,
+                             mojo::URLRequestPtr request) {
+  // Ignoring target for now.
+  base::MessageLoop::current()->PostTask(FROM_HERE,
+      base::Bind(&Engine::LoadURL, GetWeakPtr(), request->url));
+}
+
+void Engine::DidNavigateLocally(const mojo::String& url) {
+}
+
 }  // namespace shell
 }  // namespace sky