[Offline pages] Filter out pages cached by different tabs on tab helper

chrome/browser/android/offline_pages/offline_page_tab_helper.h

Index: chrome/browser/android/offline_pages/offline_page_tab_helper.h
diff --git a/chrome/browser/android/offline_pages/offline_page_tab_helper.h b/chrome/browser/android/offline_pages/offline_page_tab_helper.h
index 7e3d35d7f5fade672db93b1b387bbe9139d4e776..af283e22b529c82a9280c3a39737383927bd13c7 100644
--- a/chrome/browser/android/offline_pages/offline_page_tab_helper.h
+++ b/chrome/browser/android/offline_pages/offline_page_tab_helper.h
@@ -25,6 +25,15 @@ class OfflinePageTabHelper :
     public content::WebContentsObserver,
     public content::WebContentsUserData<OfflinePageTabHelper> {
  public:
+  // Delegate that is used to better handle external dependencies.
+  // Default implementation is in .cc file, while tests provide an override.
+  class Delegate {
+   public:
+    virtual ~Delegate() {}
+    virtual bool GetTabId(content::WebContents* web_contents,
+                          std::string* tab_id) const = 0;
+  };
+
   ~OfflinePageTabHelper() override;
 
   const OfflinePageItem* offline_page() { return offline_page_.get(); }
@@ -43,6 +52,8 @@ class OfflinePageTabHelper :
 
   explicit OfflinePageTabHelper(content::WebContents* web_contents);
 
+  void SetDelegateForTesting(std::unique_ptr<Delegate> delegate);
+
   // Overridden from content::WebContentsObserver:
   void DidStartNavigation(
       content::NavigationHandle* navigation_handle) override;
@@ -51,9 +62,19 @@ class OfflinePageTabHelper :
 
   void RedirectToOnline(const GURL& from_url,
                         const OfflinePageItem* offline_page);
+
+  // 3 step redirection to the offline page. First getting all the pages, then
+  // selecting appropriate page to redirect to and finally attempting to
+  // redirect to that offline page, and caching metadata of that page locally.
+  void GetPagesForRedirectToOffline(const GURL& online_url,
+                                    RedirectReason reason);
+  void SelectBestPageForRedirectToOffline(
+      const GURL& online_url,
+      RedirectReason reason,
+      const MultipleOfflinePageItemResult& pages);
   void TryRedirectToOffline(RedirectReason redirect_reason,
                             const GURL& from_url,
-                            const OfflinePageItem* offline_page);
+                            const OfflinePageItem& offline_page);
 
   void Redirect(const GURL& from_url, const GURL& to_url);
 
@@ -61,6 +82,7 @@ class OfflinePageTabHelper :
   // |offline_page_| will be non-null.  This can be used to synchronously ask
   // about the offline state of the current web contents.
   std::unique_ptr<OfflinePageItem> offline_page_;
+  std::unique_ptr<Delegate> delegate_;
   base::WeakPtrFactory<OfflinePageTabHelper> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(OfflinePageTabHelper);