TopSites: various small cleanups

components/history/core/browser/top_sites_impl.h

 // Copyright (c) 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_HISTORY_CORE_BROWSER_TOP_SITES_IMPL_H_
 #define COMPONENTS_HISTORY_CORE_BROWSER_TOP_SITES_IMPL_H_
 
 #include <stddef.h>
 
 #include <list>
 #include <set>
 #include <string>
 #include <utility>
 #include <vector>
 
 #include "base/callback.h"
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/scoped_observer.h"
 #include "base/synchronization/lock.h"
 #include "base/task/cancelable_task_tracker.h"
 #include "base/threading/thread_checker.h"
 #include "base/time/time.h"
 #include "base/timer/timer.h"
-#include "components/history/core/browser/history_service.h"
 #include "components/history/core/browser/history_service_observer.h"
 #include "components/history/core/browser/history_types.h"
-#include "components/history/core/browser/page_usage_data.h"
 #include "components/history/core/browser/top_sites.h"
 #include "components/history/core/browser/top_sites_backend.h"
 #include "components/history/core/common/thumbnail_score.h"
 #include "third_party/skia/include/core/SkColor.h"
 #include "ui/gfx/image/image.h"
 #include "url/gurl.h"
 
 class PrefRegistrySimple;
 class PrefService;
 
@@ skipping 101 matching lines @@
   // The URLs that are in "new" but not "old" will be have their index into
   // "new" put in |added_urls|. The non-forced URLs that are in "old" but not
   // "new" will have their index into "old" put into |deleted_urls|.
   //
   // URLs appearing in both old and new lists but having different indices will
   // have their index into "new" be put into |moved_urls|.
   static void DiffMostVisited(const MostVisitedURLList& old_list,
                               const MostVisitedURLList& new_list,
                               TopSitesDelta* delta);
 
-  // Sets the thumbnail without writing to the database. Useful when
-  // reading last known top sites from the DB.
+  // Sets the thumbnail without writing to the database.
   // Returns true if the thumbnail was set, false if the existing one is better.
   bool SetPageThumbnailNoDB(const GURL& url,
                             const base::RefCountedMemory* thumbnail_data,
                             const ThumbnailScore& score);
 
   // A version of SetPageThumbnail that takes RefCountedBytes as
   // returned by HistoryService.
   bool SetPageThumbnailEncoded(const GURL& url,
                                const base::RefCountedMemory* thumbnail,
                                const ThumbnailScore& score);
 
   // Encodes the bitmap to bytes for storage to the db. Returns true if the
   // bitmap was successfully encoded.
   static bool EncodeBitmap(const gfx::Image& bitmap,
                            scoped_refptr<base::RefCountedBytes>* bytes);
 
-  // Removes the cached thumbnail for url. Does nothing if |url| if not cached
+  // Removes the cached thumbnail for |url|. Does nothing if |url| is not cached
   // in |temp_images_|.
   void RemoveTemporaryThumbnailByURL(const GURL& url);
 
-  // Add a thumbnail for an unknown url. See temp_thumbnails_map_.
+  // Add a thumbnail for an unknown url. See |temp_images_|.
   void AddTemporaryThumbnail(const GURL& url,
-                             const base::RefCountedMemory* thumbnail,
+                             base::RefCountedMemory* thumbnail,
                              const ThumbnailScore& score);
 
   // Called by our timer. Starts the query for the most visited sites.
   void TimerFired();
 
   // Finds the given URL in the redirect chain for the given TopSite, and
   // returns the distance from the destination in hops that the given URL is.
   // The URL is assumed to be in the list. The destination is 0.
   static int GetRedirectDistanceForURL(const MostVisitedURL& most_visited,
                                        const GURL& url);
 
   // Add prepopulated pages: 'welcome to Chrome' and themes gallery to |urls|.
   // Returns true if any pages were added.
   bool AddPrepopulatedPages(MostVisitedURLList* urls,
-                            size_t num_forced_urls);
+                            size_t num_forced_urls) const;
 
   // Add all the forced URLs from |cache_| into |new_list|, making sure not to
   // add any URL that's already in |new_list|'s non-forced URLs. The forced URLs
   // in |cache_| and |new_list| are assumed to appear at the front of the list
   // and be sorted in increasing |last_forced_time|. This will still be true
   // after the call. If the list of forced URLs overflows the older ones are
   // dropped. Returns the number of forced URLs after the merge.
-  size_t MergeCachedForcedURLs(MostVisitedURLList* new_list);
+  size_t MergeCachedForcedURLs(MostVisitedURLList* new_list) const;
 
   // Takes |urls|, produces it's copy in |out| after removing blacklisted URLs.
   // Also ensures we respect the maximum number of forced URLs and non-forced
   // URLs.
   void ApplyBlacklist(const MostVisitedURLList& urls, MostVisitedURLList* out);
 
   // Returns an MD5 hash of the URL. Hashing is required for blacklisted URLs.
-  std::string GetURLHash(const GURL& url);
+  static std::string GetURLHash(const GURL& url);
 
   // Returns the delay until the next update of history is needed.
-  // Uses num_urls_changed
-  base::TimeDelta GetUpdateDelay();
+  // Uses |last_num_urls_changed_|.
+  base::TimeDelta GetUpdateDelay() const;
 
   // Updates URLs in |cache_| and the db (in the background).
   // The non-forced URLs in |new_top_sites| replace those in |cache_|.
   // The forced URLs of |new_top_sites| are merged with those in |cache_|,
   // if the list of forced URLs overflows, the oldest ones are dropped.
   // All mutations to cache_ *must* go through this. Should
   // be called from the UI thread.
   void SetTopSites(const MostVisitedURLList& new_top_sites,
                    const CallLocation location);
 
@@ skipping 30 matching lines @@
 
   // Ensures that non thread-safe methods are called on the correct thread.
   base::ThreadChecker thread_checker_;
 
   scoped_refptr<TopSitesBackend> backend_;
 
   // The top sites data.
   std::unique_ptr<TopSitesCache> cache_;
 
   // Copy of the top sites data that may be accessed on any thread (assuming
-  // you hold |lock_|). The data in |thread_safe_cache_| has blacklisted and
-  // pinned urls applied (|cache_| does not).
+  // you hold |lock_|). The data in |thread_safe_cache_| has blacklisted urls
+  // applied (|cache_| does not).
   std::unique_ptr<TopSitesCache> thread_safe_cache_;
 
   // Lock used to access |thread_safe_cache_|.
   mutable base::Lock lock_;
 
   // Task tracker for history and backend requests.
   base::CancelableTaskTracker cancelable_task_tracker_;
 
   // Timer that asks history for the top sites. This is used to make sure our
   // data stays in sync with history.
   base::OneShotTimer timer_;
 
   // The time we started |timer_| at. Only valid if |timer_| is running.
   base::TimeTicks timer_start_time_;
 
   // The number of URLs changed on the last update.
   size_t last_num_urls_changed_;
 
   // The pending requests for the top sites list. Can only be non-empty at
   // startup. After we read the top sites from the DB, we'll always have a
   // cached list and be able to run callbacks immediately.
   PendingCallbacks pending_callbacks_;
 
   // Stores thumbnails for unknown pages. When SetPageThumbnail is
   // called, if we don't know about that URL yet and we don't have
   // enough Top Sites (new profile), we store it until the next
-  // SetNonForcedTopSites call.
+  // SetTopSites call.
   TempImages temp_images_;
 
   // URL List of prepopulated page.
-  PrepopulatedPageList prepopulated_pages_;
+  const PrepopulatedPageList prepopulated_pages_;
 
   // PrefService holding the NTP URL blacklist dictionary. Must outlive
   // TopSitesImpl.
   PrefService* pref_service_;
 
   // HistoryService that TopSitesImpl can query. May be null, but if defined it
   // must outlive TopSitesImpl.
   HistoryService* history_service_;
 
   // Can URL be added to the history?
   CanAddURLToHistoryFn can_add_url_to_history_;
 
   // Are we loaded?
   bool loaded_;
 
   // Have the SetTopSites execution time related histograms been recorded?
   // The histogram should only be recorded once for each Chrome execution.
   static bool histogram_recorded_;
 
   ScopedObserver<HistoryService, HistoryServiceObserver>
       history_service_observer_;
 
   DISALLOW_COPY_AND_ASSIGN(TopSitesImpl);
 };
 
 }  // namespace history
 
 #endif  // COMPONENTS_HISTORY_CORE_BROWSER_TOP_SITES_IMPL_H_