Fix regression with back-button not working on prerendered and instant pages.

content/renderer/render_view.cc

 // Copyright (c) 2011 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.
 
 #include "content/renderer/render_view.h"
 
 #include <algorithm>
 #include <cmath>
 #include <string>
 #include <vector>
@@ skipping 685 matching lines @@
     IPC_MESSAGE_HANDLER(ViewMsg_ContextMenuClosed, OnContextMenuClosed)
     // TODO(viettrungluu): Move to a separate message filter.
 #if defined(ENABLE_FLAPPER_HACKS)
     IPC_MESSAGE_HANDLER(PepperMsg_ConnectTcpACK, OnConnectTcpACK)
 #endif
 #if defined(OS_MACOSX)
     IPC_MESSAGE_HANDLER(ViewMsg_SetInLiveResize, OnSetInLiveResize)
 #endif
     IPC_MESSAGE_HANDLER(ViewMsg_UpdateRemoteAccessClientFirewallTraversal,
                         OnUpdateRemoteAccessClientFirewallTraversal)
+    IPC_MESSAGE_HANDLER(ViewMsg_OffsetAndPruneHistory,
+                        OnOffsetAndPruneHistory)
     // Have the super handle all other messages.
     IPC_MESSAGE_UNHANDLED(handled = RenderWidget::OnMessageReceived(message))
   IPC_END_MESSAGE_MAP()
   return handled;
 }
 
 void RenderView::OnNavigate(const ViewMsg_Navigate_Params& params) {
   if (!webview())
     return;
 
@@ skipping 294 matching lines @@
 void RenderView::OnScrollFocusedEditableNodeIntoView() {
   WebKit::WebNode node = GetFocusedNode();
   if (!node.isNull()) {
     if (IsEditableNode(node))
       // TODO(varunjain): Change webkit API to scroll a particular node into
       // view and use that API here instead.
       webview()->scrollFocusedNodeIntoView();
   }
 }
 
+void RenderView::OnOffsetAndPruneHistory(int offset) {
+  int current_page_id = -1;

[tburkard, 2011/08/09 17:36:03]

I'd add a comment explaining what this does (either here or in the headerfile)

[cbentzel, 2011/08/09 19:12:14]

I did this at the ViewMsg declaration, which looked more consistent.

+  if (history_list_offset_ >= 0) {

[brettw, 2011/08/09 18:14:40]

No {} for single-line conditionals.

[cbentzel, 2011/08/09 19:12:14]

Done.

+    current_page_id = history_page_ids_[history_list_offset_];
+  }
+
+  history_list_offset_ = offset;
+  history_list_length_ = offset + 1;
+  if (history_list_length_ >= 0)

[brettw, 2011/08/09 18:14:40]

What case will the history_list_length_ be negative? That seems suspicious.

[cbentzel, 2011/08/09 19:12:14]

That would be suspicious. Removed during the migration to the new version. I do
still check for negative history_list_offset_ because this may be swapped in
after a Navigate message but before a didCommitProvisionalLoad.

+    history_page_ids_.resize(history_list_length_, -1);
+  // Older entries also need to be invalidated.
+  for (int i = 0; i < history_list_offset_; ++i)

[brettw, 2011/08/09 18:14:40]

I think this version is a bit easier to follow:

// <clear comment about what type of list we're trying to generate>.
std::vector<int32> new_page_ids_;
new_page_ids.resize(history_list_length_, -1);
new_page_ids[history_list_offset_] = current_page_id;
history_page_ids.swap(new_page_ids);

[cbentzel, 2011/08/09 19:12:14]

Yes, that's cleaner. Moved to that.

+    history_page_ids_[i] = -1;
+  history_page_ids_[history_list_offset_] = current_page_id;
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 
 // Tell the embedding application that the URL of the active page has changed
 void RenderView::UpdateURL(WebFrame* frame) {
   WebDataSource* ds = frame->dataSource();
   DCHECK(ds);
 
   const WebURLRequest& request = ds->request();
   const WebURLRequest& original_request = ds->originalRequest();
   const WebURLResponse& response = ds->response();
@@ skipping 3432 matching lines @@
 }
 #endif
 
 void RenderView::OnContextMenuClosed(
     const webkit_glue::CustomContextMenuContext& custom_context) {
   if (custom_context.is_pepper_menu)
     pepper_delegate_.OnContextMenuClosed(custom_context);
   else
     context_menu_node_.reset();
 }