Add last_requested field to the favicon_bitmaps table of the favicons database.

components/history/core/browser/history_types.h

Index: components/history/core/browser/history_types.h
diff --git a/components/history/core/browser/history_types.h b/components/history/core/browser/history_types.h
index cbcf26b75b7d453fe321606dd41e6a7b5999d0ad..d27f1e86b3f03a89d33f5f4587db3c6288a95bdb 100644
--- a/components/history/core/browser/history_types.h
+++ b/components/history/core/browser/history_types.h
@@ -497,6 +497,9 @@ struct FaviconBitmap {
   // Time at which |bitmap_data| was last updated.
   base::Time last_updated;
 
+  // Time at which |bitmap_data| was last requested.
+  base::Time last_requested;
+
   // The bits of the bitmap.
   scoped_refptr<base::RefCountedMemory> bitmap_data;