TopSites: various small cleanups

components/history/core/browser/top_sites_cache.h

 // Copyright (c) 2012 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_HISTORY_CORE_BROWSER_TOP_SITES_CACHE_H_
 #define COMPONENTS_HISTORY_CORE_BROWSER_TOP_SITES_CACHE_H_
 
 #include <stddef.h>
 
 #include <map>
 #include <utility>
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "components/history/core/browser/history_types.h"
 #include "components/history/core/browser/url_utils.h"
 #include "url/gurl.h"
 
-class GURL;
-
 namespace history {
 
-// TopSiteCache caches thumbnails for visited pages. Retrieving thumbnails from
-// a given input URL is a two-stage process:
+// TopSitesCache caches the top sites and thumbnails for TopSites.
+//
+// Retrieving thumbnails from a given input URL is a two-stage process:
 //
 //   input URL --(map 1)--> canonical URL --(map 2)--> image.
 //
 // (map 1) searches for an URL in |canonical_urls_| that "matches" (see below)
 // input URL. If found, canonical URL assigned to the result. Otherwise the
 // input URL is considered to already be a canonical URL.
 //
 // (map 2) simply looks up canonical URL in |images_|.
 //
 // The rule to "match" URL in |canonical_urls_| always favors exact match.
 // - In GetCanonicalURL(), exact match is the only case examined.
 // - In GetGeneralizedCanonicalURL(), we also perform "generalized" URL matches,
 //   i.e., stored URLs in |canonical_urls_| that are prefixes of input URL,
 //   ignoring "?query#ref".
 // For the latter two "URL prefix matches", we prefer the match that is closest
 // to input URL, w.r.t. path hierarchy.
-
-// TopSitesCache caches the top sites and thumbnails for TopSites.
 class TopSitesCache {
  public:
   TopSitesCache();
   ~TopSitesCache();
 
   // Set the top sites. In |top_sites| all forced URLs must appear before
   // non-forced URLs. This is only checked in debug.
   void SetTopSites(const MostVisitedURLList& top_sites);
   const MostVisitedURLList& top_sites() const { return top_sites_; }
 
@@ skipping 111 matching lines @@
   // Helper to clear "/path?query#ref" from any GURL. This is set in the
   // constructor and never modified after.
   GURL::Replacements clear_path_query_ref_;
 
   DISALLOW_COPY_AND_ASSIGN(TopSitesCache);
 };
 
 }  // namespace history
 
 #endif  // COMPONENTS_HISTORY_CORE_BROWSER_TOP_SITES_CACHE_H_