Fix bug in shut down of HTMLViewer

components/font_service/public/cpp/font_loader.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 "components/font_service/public/cpp/font_loader.h"
 
 #include "base/bind.h"
 #include "components/font_service/public/cpp/font_service_thread.h"
 #include "mojo/application/public/cpp/application_impl.h"
 #include "mojo/application/public/cpp/connect.h"
@@ skipping 21 matching lines @@
   mojo::URLRequestPtr request(mojo::URLRequest::New());
   request->url = mojo::String::From("mojo:font_service");
   FontServicePtr font_service;
   application_impl->ConnectToService(request.Pass(), &font_service);
 
   thread_ = new internal::FontServiceThread(font_service.Pass());
 }
 
 FontLoader::~FontLoader() {}
 
+void FontLoader::Shutdown() {
+  thread_->Stop();
+  thread_ = nullptr;
+}
+
 bool FontLoader::matchFamilyName(const char family_name[],
                                  SkTypeface::Style requested,
                                  FontIdentity* out_font_identifier,
                                  SkString* out_family_name,
                                  SkTypeface::Style* out_style) {
   return thread_->MatchFamilyName(family_name, requested, out_font_identifier,
                                   out_family_name, out_style);
 }
 
 SkStreamAsset* FontLoader::openStream(const FontIdentity& identity) {
@@ skipping 21 matching lines @@
     return mapped_font_files_it->second->CreateMemoryStream();
   }
 }
 
 void FontLoader::OnMappedFontFileDestroyed(internal::MappedFontFile* f) {
   base::AutoLock lock(lock_);
   mapped_font_files_.erase(f->font_id());
 }
 
 }  // namespace font_service