Add revalidation_only option to precache config.

components/precache/core/precache_fetcher.h

 // Copyright 2013 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.
 
 #ifndef COMPONENTS_PRECACHE_CORE_PRECACHE_FETCHER_H_
 #define COMPONENTS_PRECACHE_CORE_PRECACHE_FETCHER_H_
 
 #include <stdint.h>
 
 #include <deque>
@@ skipping 281 matching lines @@
 // network_url_fetcher() will return nullptr.
 class PrecacheFetcher::Fetcher : public net::URLFetcherDelegate {
  public:
   // Construct a new Fetcher. This will create and start a new URLFetcher for
   // the specified URL using the specified request context.
   Fetcher(net::URLRequestContextGetter* request_context,
           const GURL& url,
           const std::string& referrer,
           const base::Callback<void(const Fetcher&)>& callback,
           bool is_resource_request,
-          size_t max_bytes);
+          size_t max_bytes,
+          bool revalidation_only);

[bengr, 2017/01/11 20:08:46]

Please add a description of parameters to the method comment.

[twifkak, 2017/01/11 20:40:15]

Done.

   ~Fetcher() override;
   void OnURLFetchDownloadProgress(const net::URLFetcher* source,
                                   int64_t current,
                                   int64_t total,
                                   int64_t current_network_bytes) override;
   void OnURLFetchComplete(const net::URLFetcher* source) override;
   int64_t response_bytes() const { return response_bytes_; }
   int64_t network_response_bytes() const { return network_response_bytes_; }
   const net::URLFetcher* network_url_fetcher() const {
     return network_url_fetcher_.get();
   }
   const GURL& url() const { return url_; }
   const std::string& referrer() const { return referrer_; }
   bool is_resource_request() const { return is_resource_request_; }
   bool was_cached() const { return was_cached_; }
 
  private:
   enum class FetchStage { CACHE, NETWORK };
 
   void LoadFromCache();
   void LoadFromNetwork();
 
   net::URLRequestContextGetter* const request_context_;
   const GURL url_;
   const std::string referrer_;
   const base::Callback<void(const Fetcher&)> callback_;
   const bool is_resource_request_;
   const size_t max_bytes_;
+  const bool revalidation_only_;

[bengr, 2017/01/11 20:08:46]

is_resource_request_, max_bytes_, and revalidation_only aren't obviously self
descriptive. Please add commments.

[twifkak, 2017/01/11 20:40:15]

OK, added parameter comments to the constructor, and a one-liner here to refer
to the constructor.

 
   FetchStage fetch_stage_;
   // The cache_url_fetcher_ is kept alive until Fetcher destruction for testing.
   std::unique_ptr<net::URLFetcher> cache_url_fetcher_;
   std::unique_ptr<net::URLFetcher> network_url_fetcher_;
   int64_t response_bytes_;
   int64_t network_response_bytes_;
   bool was_cached_;
 
   DISALLOW_COPY_AND_ASSIGN(Fetcher);
 };
 
 }  // namespace precache
 
 #endif  // COMPONENTS_PRECACHE_CORE_PRECACHE_FETCHER_H_