Add item and document sequence numbers to FrameNavigationEntry.

content/browser/frame_host/frame_navigation_entry.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_BROWSER_FRAME_HOST_FRAME_NAVIGATION_ENTRY_H_
 #define CONTENT_BROWSER_FRAME_HOST_FRAME_NAVIGATION_ENTRY_H_
 
 #include "base/basictypes.h"
 #include "base/memory/ref_counted.h"
 #include "content/browser/site_instance_impl.h"
 #include "content/public/common/page_state.h"
 #include "content/public/common/referrer.h"
 
 namespace content {
 
 // Represents a session history item for a particular frame.
 //
 // This class is refcounted and can be shared across multiple NavigationEntries.
 // For now, it is owned by a single NavigationEntry and only tracks the main
 // frame.
 //
 // TODO(creis): In --site-per-process, fill in a tree of FrameNavigationEntries
 // in each NavigationEntry, one per frame.  FrameNavigationEntries may be shared
 // across NavigationEntries if the frame hasn't changed.
 class CONTENT_EXPORT FrameNavigationEntry
     : public base::RefCounted<FrameNavigationEntry> {
  public:
   // TODO(creis): We should not use FTN IDs here, since they will change if you
   // leave a page and come back later.  We should evaluate whether Blink's
-  // frame sequence numbers or unique names would work instead, similar to
-  // HistoryNode.
+  // unique names would work instead, similar to HistoryNode.
   explicit FrameNavigationEntry(int64 frame_tree_node_id);
   FrameNavigationEntry(int64 frame_tree_node_id,
+                       int64 item_sequence_number,
+                       int64 document_sequence_number,
                        SiteInstanceImpl* site_instance,
                        const GURL& url,
                        const Referrer& referrer);
 
   // Creates a copy of this FrameNavigationEntry that can be modified
   // independently from the original.
   FrameNavigationEntry* Clone() const;
 
   // Updates all the members of this entry.
-  void UpdateEntry(SiteInstanceImpl* site_instance,
+  void UpdateEntry(int64 item_sequence_number,
+                   int64 document_sequence_number,
+                   SiteInstanceImpl* site_instance,
                    const GURL& url,
                    const Referrer& referrer,
                    const PageState& page_state);
 
   // The ID of the FrameTreeNode this entry is for.  -1 for the main frame,
   // since we don't always know the FrameTreeNode ID when creating the overall
   // NavigationEntry.
   // TODO(creis): Replace with frame sequence number or unique name.
   int64 frame_tree_node_id() const { return frame_tree_node_id_; }
 
+  // Keeps track of where this entry belongs in the frame's session history.
+  // The item sequence number identifies each stop in the back/forward history
+  // and is globally unique.  The document sequence number increments for each
+  // new document and is also globally unique.  In-page navigations get a new
+  // item sequence number but the same document sequence number.

[Avi (use Gerrit), 2015/06/18 20:36:07]

Update this comment to explain "globally unique" like you do below.

+  void set_item_sequence_number(int64 item_sequence_number) {
+    item_sequence_number_ = item_sequence_number;
+  }
+  int64 item_sequence_number() { return item_sequence_number_; }
+  void set_document_sequence_number(int64 document_sequence_number) {
+    document_sequence_number_ = document_sequence_number;
+  }
+  int64 document_sequence_number() { return document_sequence_number_; }
+
   // The SiteInstance responsible for rendering this frame.  All frames sharing
   // a SiteInstance must live in the same process.  This is a refcounted pointer
   // that keeps the SiteInstance (not necessarily the process) alive as long as
   // this object remains in the session history.
   void set_site_instance(SiteInstanceImpl* site_instance) {
     site_instance_ = site_instance;
   }
   SiteInstanceImpl* site_instance() const { return site_instance_.get(); }
 
   // The actual URL loaded in the frame.  This is in contrast to the virtual
@@ skipping 13 matching lines @@
   virtual ~FrameNavigationEntry();
 
   // WARNING WARNING WARNING WARNING WARNING WARNING WARNING WARNING WARNING
   // For all new fields, update |Clone|.
   // TODO(creis): These fields have implications for session restore.  This is
   // currently managed by NavigationEntry, but the logic will move here.
   // WARNING WARNING WARNING WARNING WARNING WARNING WARNING WARNING WARNING
 
   // See the accessors above for descriptions.
   int64 frame_tree_node_id_;
+  int64 item_sequence_number_;
+  int64 document_sequence_number_;
   scoped_refptr<SiteInstanceImpl> site_instance_;
   GURL url_;
   Referrer referrer_;
   // TODO(creis): Change this to FrameState.
   PageState page_state_;
 
   DISALLOW_COPY_AND_ASSIGN(FrameNavigationEntry);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_FRAME_HOST_FRAME_NAVIGATION_ENTRY_H_