Report downloaded resources at most once

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 33c9a97adf252d1576f52fb2c2e55347babacc8c..83dd4feebfd72b1d88d6308024cfe6b7f0e8d50d 100644
--- a/components/precache/core/precache_fetcher.h
+++ b/components/precache/core/precache_fetcher.h
@@ -49,7 +49,7 @@ struct ManifestHostInfo {
                    const std::string& hostname,
                    int64_t visits,
                    const std::string& used_url_hash,
-                   const std::string& unused_url_hash);
+                   const std::string& downloaded_url_hash);
   ~ManifestHostInfo();
   ManifestHostInfo(ManifestHostInfo&&);
   ManifestHostInfo& operator=(ManifestHostInfo&&);
@@ -60,7 +60,7 @@ struct ManifestHostInfo {
   GURL manifest_url;
   int64_t visits;
   std::string used_url_hash;
-  std::string unused_url_hash;
+  std::string downloaded_url_hash;
 };
 
 // Information about a resource to be downloaded.