Change the RecentTabHelper to only capture the last one page in a tab.

chrome/browser/android/offline_pages/recent_tab_helper.h

Index: chrome/browser/android/offline_pages/recent_tab_helper.h
diff --git a/chrome/browser/android/offline_pages/recent_tab_helper.h b/chrome/browser/android/offline_pages/recent_tab_helper.h
index 025f52b8fbce9d61a67d79cb7270e2b931dd1321..c5db7362834dc1c76337bd71251c9ff8910ba7b3 100644
--- a/chrome/browser/android/offline_pages/recent_tab_helper.h
+++ b/chrome/browser/android/offline_pages/recent_tab_helper.h
@@ -51,13 +51,20 @@ class RecentTabHelper
     virtual std::unique_ptr<OfflinePageArchiver> CreateArchiver(
         content::WebContents* web_contents) = 0;
   };
-  // Test method, overrides the normally used MHTML Archivers with a test
-  // mocks created by specified function.
-  void SetArchiveFactoryForTest(
-      std::unique_ptr<TestArchiveFactory> test_archive_factory);
-  // Test method, overrides the task_runner_ so FastForwardBy() can be used.
-  void SetTaskRunnerForTest(
-      const scoped_refptr<base::SingleThreadTaskRunner>& task_runner);
+
+
+  // Delegate that is used by RecentTabHelper to get external dependencies.
+  // Default implementation lives in .cc file, while tests provide an override.
+  class Delegate {
+   public:
+    virtual ~Delegate() {}
+    virtual std::unique_ptr<OfflinePageArchiver> CreatePageArchiver(
+        content::WebContents* web_contents) = 0;
+    virtual scoped_refptr<base::SingleThreadTaskRunner> GetTaskRunner() = 0;
+    // There is no expectations that tab_id is always present.
+    virtual bool GetTabId(int* tab_id, content::WebContents* web_contents) = 0;
+  };
+  void Initialize(std::unique_ptr<RecentTabHelper::Delegate> delegate);
 
  private:
   explicit RecentTabHelper(content::WebContents* web_contents);
@@ -75,15 +82,17 @@ class RecentTabHelper
 
   // Page model is a service, no ownership.
   OfflinePageModel* page_model_;
-
   // If true, never make snapshots off the attached WebContents.
   bool never_do_snapshots_;
+  // If empty, the tab does not have AndroidId and can not capture pages.
+  std::string tab_id_;
 
   // The URL of the page that is currently being snapshotted. Used to check,
   // during async operations, that WebContents still contains the same page.
   GURL snapshot_url_;
   std::unique_ptr<SnapshotController> snapshot_controller_;
-  std::unique_ptr<TestArchiveFactory> test_archive_factory_;
+
+  std::unique_ptr<Delegate> delegate_;
 
   base::WeakPtrFactory<RecentTabHelper> weak_ptr_factory_;