Remove unused last_forced_time from MostVisitedURL

Missed this during the initial deprecation. last_forced_time is now
unused.

Bug: 893362
Change-Id: I907befacea250a0bb8e971c78dab0124e5a39c1a
Reviewed-on: https://chromium-review.googlesource.com/c/1388816
Commit-Queue: Kristi Park <kristipark@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#618679}

components/history/core/browser/history_types.cc

@@ -177,10 +177,8 @@ QueryURLResult::~QueryURLResult() {
 
 MostVisitedURL::MostVisitedURL() {}
 
-MostVisitedURL::MostVisitedURL(const GURL& url,
-                               const base::string16& title,
-                               base::Time last_forced_time)
-    : url(url), title(title), last_forced_time(last_forced_time) {}
+MostVisitedURL::MostVisitedURL(const GURL& url, const base::string16& title)
+    : url(url), title(title) {}
 
 MostVisitedURL::MostVisitedURL(const GURL& url,
                                const base::string16& title,

components/history/core/browser/history_types.h

@@ -299,9 +299,7 @@ struct VisibleVisitCountToHostResult {
 // Holds the per-URL information of the most visited query.
 struct MostVisitedURL {
   MostVisitedURL();
-  MostVisitedURL(const GURL& url,
-                 const base::string16& title,
-                 base::Time last_forced_time = base::Time());
+  MostVisitedURL(const GURL& url, const base::string16& title);
   MostVisitedURL(const GURL& url,
                  const base::string16& title,
                  const RedirectList& preceding_redirects);
@@ -316,11 +314,6 @@ struct MostVisitedURL {
   GURL url;
   base::string16 title;
 
-  // If this is a URL for which we want to force a thumbnail, records the last
-  // time it was forced so we can evict it when more recent URLs are requested.
-  // If it's not a forced thumbnail, keep a time of 0.
-  base::Time last_forced_time;
-
   RedirectList redirects;
 
   MostVisitedURL& operator=(const MostVisitedURL&);