Mojo HTML viewer crash

mojo/services/html_viewer/html_document.cc

 // Copyright 2014 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 "mojo/services/html_viewer/html_document.h"
 
 #include "base/bind.h"
 #include "base/location.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop/message_loop_proxy.h"
@@ skipping 225 matching lines @@
 blink::WebNavigationPolicy HTMLDocument::decidePolicyForNavigation(
     blink::WebLocalFrame* frame,
     blink::WebDataSource::ExtraData* data,
     const blink::WebURLRequest& request,
     blink::WebNavigationType nav_type,
     blink::WebNavigationPolicy default_policy,
     bool is_redirect) {
   if (CanNavigateLocally(frame, request))
     return default_policy;
 
-  navigator_host_->RequestNavigate(
-      WebNavigationPolicyToNavigationTarget(default_policy),
-      mojo::URLRequest::From(request).Pass());
+  if (navigator_host_.get()) {
+    navigator_host_->RequestNavigate(
+        WebNavigationPolicyToNavigationTarget(default_policy),
+        mojo::URLRequest::From(request).Pass());
+  }
 
   return blink::WebNavigationPolicyIgnore;
 }
 
 void HTMLDocument::didAddMessageToConsole(
     const blink::WebConsoleMessage& message,
     const blink::WebString& source_name,
     unsigned source_line,
     const blink::WebString& stack_trace) {
 }
 
 void HTMLDocument::didNavigateWithinPage(
     blink::WebLocalFrame* frame,
     const blink::WebHistoryItem& history_item,
     blink::WebHistoryCommitType commit_type) {
-  navigator_host_->DidNavigateLocally(history_item.urlString().utf8());
+  if (navigator_host_.get())
+    navigator_host_->DidNavigateLocally(history_item.urlString().utf8());
 }
 
 blink::WebEncryptedMediaClient* HTMLDocument::encryptedMediaClient() {
   if (!web_encrypted_media_client_) {
     web_encrypted_media_client_ = new media::WebEncryptedMediaClientImpl(
         make_scoped_ptr(new media::DefaultCdmFactory()));
   }
   return web_encrypted_media_client_;
 }
 
@@ skipping 11 matching lines @@
 }
 
 void HTMLDocument::OnViewInputEvent(View* view, const mojo::EventPtr& event) {
   scoped_ptr<blink::WebInputEvent> web_event =
       event.To<scoped_ptr<blink::WebInputEvent>>();
   if (web_event)
     web_view_->handleInputEvent(*web_event);
 }
 
 }  // namespace html_viewer