Fix handling of failed distillation.

components/dom_distiller/standalone/content_extractor.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 <sstream>
 
 #include "base/command_line.h"
 #include "base/files/scoped_temp_dir.h"
 #include "base/message_loop/message_loop.h"
 #include "base/path_service.h"
@@ skipping 187 matching lines @@
 
  private:
   ContentExtractionRequest(const GURL& url) : url_(url) {}
 
   virtual void OnArticleUpdated(ArticleDistillationUpdate article_update)
       OVERRIDE {}
 
   virtual void OnArticleReady(const DistilledArticleProto* article_proto)
       OVERRIDE {
     article_proto_ = article_proto;
+    CHECK(article_proto->pages_size()) << "Failed extracting " << url_;
     base::MessageLoop::current()->PostTask(
         FROM_HERE,
         finished_callback_);
   }
 
   const DistilledArticleProto* article_proto_;
   scoped_ptr<ViewerHandle> viewer_handle_;
   GURL url_;
   base::Closure finished_callback_;
 };
@@ skipping 113 matching lines @@
   std::string output_data_;
   scoped_ptr<google::protobuf::io::StringOutputStream> protobuf_output_stream_;
 };
 
 IN_PROC_BROWSER_TEST_F(ContentExtractor, MANUAL_ExtractUrl) {
   Start();
   base::RunLoop().Run();
 }
 
 }  // namespace dom_distiller