[Thumbnails DB] Allow setting last_requested time when accessing favicons.

components/history/core/browser/thumbnail_database.h

Index: components/history/core/browser/thumbnail_database.h
diff --git a/components/history/core/browser/thumbnail_database.h b/components/history/core/browser/thumbnail_database.h
index 9f81d41f46daca2f9078e6d7f54a0bd2ea3099dd..d553f35b40b2b228432a8adf494101db006ab1ec 100644
--- a/components/history/core/browser/thumbnail_database.h
+++ b/components/history/core/browser/thumbnail_database.h
@@ -62,6 +62,11 @@ class ThumbnailDatabase {
   // true try to trim all unused cache, otherwise trim by half.
   void TrimMemory(bool aggressively);
 
+  // Delete all favicon bitmaps that have not been requested long (i.e. not
+  // after |expiration_threshold|). Furthermore, delete all favicons with no
+  // corresponding bitmap and all mappings with no corresponding favicon.
+  void CleanUnusedFavicons(base::Time expiration_threshold);
+
   // Favicon Bitmaps -----------------------------------------------------------
 
   // Returns true if there are favicon bitmaps for |icon_id|. If
@@ -80,10 +85,14 @@ class ThumbnailDatabase {
                          std::vector<FaviconBitmap>* favicon_bitmaps);
 
   // Gets the last updated time, bitmap data, and pixel size of the favicon
-  // bitmap at |bitmap_id|. Returns true if successful.
+  // bitmap at |bitmap_id|. Returns true if successful. The |access_time| is
+  // stored for |bitmap_id| (should be base::Time:Now() in most cases and
+  // base::Time() in incognito profiles to avoid storing the access). The access
+  // times are used to detect that a favicon should be removed if it has not
+  // been used for long.
   bool GetFaviconBitmap(FaviconBitmapID bitmap_id,
+                        base::Time access_time,
                         base::Time* last_updated,
-                        base::Time* last_requested,
                         scoped_refptr<base::RefCountedMemory>* png_icon_data,
                         gfx::Size* pixel_size);
 
@@ -113,11 +122,6 @@ class ThumbnailDatabase {
   bool SetFaviconBitmapLastUpdateTime(FaviconBitmapID bitmap_id,
                                       base::Time time);
 
-  // Sets the last requested time for the favicon bitmap at |bitmap_id|.
-  // Returns true if successful.
-  bool SetFaviconBitmapLastRequestedTime(FaviconBitmapID bitmap_id,
-                                         base::Time time);
-
   // Deletes the favicon bitmap with |bitmap_id|.
   // Returns true if successful.
   bool DeleteFaviconBitmap(FaviconBitmapID bitmap_id);