Last_n: do not save snapshot of custom tabs.

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 f2231957ff4e586567fd3d95dbdf2f5eeb0dc424..3f32c12056ee5a42621013b8e8ab28b0aad5eeb7 100644
--- a/chrome/browser/android/offline_pages/offline_page_utils.h
+++ b/chrome/browser/android/offline_pages/offline_page_utils.h
@@ -68,6 +68,10 @@ class OfflinePageUtils {
   // ID of the tab.
   static bool GetTabId(content::WebContents* web_contents, int* tab_id);
 
+  // Returns true if the |web_contents| is currently being presented inside a
+  // custom tab.
+  static bool CurrentlyShownInCustomTab(content::WebContents* web_contents);
+
   // Performs a check, whether pages with specified |url| and |name_space|
   // already exist. Result is returned in a |callback|, where first parameter
   // indicates whether offline pages exist, while second is a helper value to