Ensure using chrome://thumb2/... adds the URL as a forced URL in TopSites so that a thumbnail is ca…

chrome/browser/history/top_sites_impl.cc

Index: chrome/browser/history/top_sites_impl.cc
diff --git a/chrome/browser/history/top_sites_impl.cc b/chrome/browser/history/top_sites_impl.cc
index 9eb3a00694f7a060f98cdb30e5dfadc134aca212..40f78fce1bd49afb2299049a584dc73725f7eefb 100644
--- a/chrome/browser/history/top_sites_impl.cc
+++ b/chrome/browser/history/top_sites_impl.cc
@@ -607,6 +607,39 @@ bool TopSitesImpl::loaded() const {
   return loaded_;
 }
 
+bool TopSitesImpl::AddForcedURL(const GURL& url, const base::Time& time) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  size_t num_forced = cache_->GetNumForcedURLs();
+  MostVisitedURLList new_list(cache_->top_sites());
+  MostVisitedURL new_url;
+
+  if (cache_->IsKnownURL(url)) {
+    size_t index = cache_->GetURLIndex(url);
+    // Do nothing if we currently have that URL as non-forced.
+    if (new_list[index].last_forced_time.is_null())

[brettw, 2013/11/19 06:38:09]

Non-forced URLs might move around a lot. Will this mean that such URLs could get
automatically dropped off the list even though we're intending to force them?

[beaudoin, 2013/11/19 11:59:46]

I've thought about that. I don't think it will be a problem in practice:
- Forced URLs are nice-to-have but they don't offer a guarantee (we don't know
when the user will visit the website next, so we don't know when we'll have a
thumbnail for it)
- If a URL is dropped from the non-forced list chances are it's not really that
popular on this machine so it's probably not needed in the forced list. (The
forced list is mostly useful when there are small differences in the URLs
generated by Most Likely and those generated by Most Visited.)

I could keep a "bool forced" field with each MostVisitedURL so when we drop a
non-forced URL with a non-zero timestamp we'd move it to the forced list. This
is quite involved though so I strongly suggest we only do it if we notice a
problem with the current approach.

+      return false;
+
+    // Update the |last_forced_time| of the already existing URL. Delete it and
+    // reinsert it at the right location.
+    new_url = new_list[index];
+    new_list.erase(new_list.begin() + index);
+    num_forced--;
+  } else {
+    new_url.url = url;
+    new_url.redirects.push_back(url);
+  }
+  new_url.last_forced_time = time;
+  // Add forced URLs and sort. Added to the end of the list of forced URLs
+  // since this is almost always where it needs to go, unless the user's local
+  // clock is fiddled with.
+  MostVisitedURLList::iterator mid = new_list.begin() + num_forced;
+  new_list.insert(mid, new_url);
+  mid = new_list.begin() + num_forced;  // Mid was invalidated.
+  std::inplace_merge(new_list.begin(), mid, mid + 1, ForcedURLComparator);
+  SetTopSites(new_list);
+  return true;
+}
+
 bool TopSitesImpl::AddPrepopulatedPages(MostVisitedURLList* urls,
                                         size_t num_forced_urls) {
   bool added = false;