Add revalidation_only option to precache config.

components/precache/core/precache_fetcher.h

Index: components/precache/core/precache_fetcher.h
diff --git a/components/precache/core/precache_fetcher.h b/components/precache/core/precache_fetcher.h
index 83dd4feebfd72b1d88d6308024cfe6b7f0e8d50d..b0fe1582ed1462ada12709f0055fd255d5d39128 100644
--- a/components/precache/core/precache_fetcher.h
+++ b/components/precache/core/precache_fetcher.h
@@ -299,7 +299,8 @@ class PrecacheFetcher::Fetcher : public net::URLFetcherDelegate {
           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,
@@ -328,6 +329,7 @@ class PrecacheFetcher::Fetcher : public net::URLFetcherDelegate {
   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.