Add "Show saved copy" button in dino page when there's offline copy

components/offline_pages/offline_page_model.cc

Index: components/offline_pages/offline_page_model.cc
diff --git a/components/offline_pages/offline_page_model.cc b/components/offline_pages/offline_page_model.cc
index 14530042f5f892a163c81d0294aa9559f27111c5..3a03ab224433e0eb18fd27834e46fdae59cfdc0b 100644
--- a/components/offline_pages/offline_page_model.cc
+++ b/components/offline_pages/offline_page_model.cc
@@ -251,6 +251,11 @@ void OfflinePageModel::ClearAll(const base::Closure& callback) {
                  callback));
 }
 
+bool OfflinePageModel::HasOfflinePages() const {
+  DCHECK(is_loaded_);
+  return !offline_pages_.empty();
+}
+
 const std::vector<OfflinePageItem> OfflinePageModel::GetAllPages() const {
   DCHECK(is_loaded_);
   std::vector<OfflinePageItem> offline_pages;
@@ -292,6 +297,17 @@ const OfflinePageItem* OfflinePageModel::GetPageByOfflineURL(
   return nullptr;
 }
 
+const OfflinePageItem* OfflinePageModel::GetPageByOnlineURL(
+    const GURL& online_url) const {
+  for (auto iter = offline_pages_.begin();
+       iter != offline_pages_.end();
+       ++iter) {
+    if (iter->second.url == online_url)
+      return &(iter->second);
+  }
+  return nullptr;
+}
+
 void OfflinePageModel::CheckForExternalFileDeletion() {
   DCHECK(is_loaded_);