Make GetBestPageForOnlineURL async

chrome/browser/android/offline_pages/offline_page_utils.h

Index: chrome/browser/android/offline_pages/offline_page_utils.h
diff --git a/chrome/browser/android/offline_pages/offline_page_utils.h b/chrome/browser/android/offline_pages/offline_page_utils.h
index 11455ff2dc72407d4f5efc361127975f7982e138..29733c3d68604f4e269508bd8c0e75013aaf6111 100644
--- a/chrome/browser/android/offline_pages/offline_page_utils.h
+++ b/chrome/browser/android/offline_pages/offline_page_utils.h
@@ -24,6 +24,15 @@ class OfflinePageUtils {
   // Returns true if |url| might point to an offline page.
   static bool MightBeOfflineURL(const GURL& url);
 
+  // Returns via callback an offline page saved for |online_url|, if any. The
+  // best page is chosen based on creation date; a more recently created offline
+  // page will be preferred over an older one.

[Dmitry Titov, 2016/08/10 02:56:37]

please add info to the comment on why tab_id is passed in.

Also, the naming is weird. "best" from which point of view? I think this is
selecting a page for automatic redirect to offline page, perhaps the name should
reflect that. Maybe GetOfflinePageForBrowserRedirect()?

[jianli, 2016/08/11 00:33:27]

Per discussion, renamed to SelectPageForOnlineURL. Also added comment for
tab_id.

+  static void GetBestPageForOnlineURL(
+      content::BrowserContext* browser_context,
+      const GURL& online_url,
+      int tab_id,
+      const base::Callback<void(const OfflinePageItem*)>& callback);
+
   // Gets an online URL of an offline page with |offline_url| if one exists.
   // Deprecated.  Use |GetOnlineURLForOfflineURL|.
   static GURL MaybeGetOnlineURLForOfflineURL(