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 686 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_SetHistoryLengthAndClear,
+                        OnSetHistoryLengthAndClear)
     // 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::OnSetHistoryLengthAndClear(int history_length) {
+  DCHECK(history_length >= 0);
+
+  // history_list_length_ may be 0 if this is called between
+  // a navigate and a commit of the provisional load. Otherwise,
+  // only add one entry, regardless of how long the current history is.
+  // TODO(cbentzel): Investigate what happens if a prerendered page
+  //   navigates to several entries before it is swapped in. Cropping
+  //   those may be a bad idea.
+  int new_history_list_length = history_length;
+  if (history_list_length_ > 0)
+    ++new_history_list_length;
+
+  DCHECK(page_id_ == -1 ||
+         (history_list_offset_ >= 0 &&
+          page_id_ == history_page_ids_[history_list_offset_]));
+
+  // Generate the new list.
+  std::vector<int32> new_history_page_ids(new_history_list_length, -1);
+  if (page_id_ != -1)
+    new_history_page_ids[new_history_list_length - 1] = page_id_;
+  new_history_page_ids.swap(history_page_ids_);
+  history_list_offset_ = new_history_list_length - 1;
+  history_list_length_ = new_history_list_length;
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 
 // 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 3425 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();
 }