Update a comment with a link to a historic source.

content/browser/frame_host/navigation_controller_impl_unittest.cc

 // Copyright 2013 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 "base/basictypes.h"
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/files/file_util.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/stl_util.h"
@@ skipping 2032 matching lines @@
   EXPECT_TRUE(controller.RendererDidNavigate(main_test_rfh(), params,
                                              &details));
   EXPECT_EQ(1U, navigation_entry_committed_counter_);
   navigation_entry_committed_counter_ = 0;
   EXPECT_EQ(2, controller.GetEntryCount());
 
   // Second manual subframe navigation should also make a new entry.
   const GURL url3("http://foo3");
   params.page_id = 2;
   params.url = url3;
+  params.transition = ui::PAGE_TRANSITION_MANUAL_SUBFRAME;
   EXPECT_TRUE(controller.RendererDidNavigate(main_test_rfh(), params,
                                              &details));
   EXPECT_EQ(1U, navigation_entry_committed_counter_);
   navigation_entry_committed_counter_ = 0;
   EXPECT_EQ(3, controller.GetEntryCount());
   EXPECT_EQ(2, controller.GetCurrentEntryIndex());
 
   // Go back one.
   controller.GoBack();
+  params.page_id = 1;
   params.url = url2;
-  params.page_id = 1;
+  params.transition = ui::PAGE_TRANSITION_AUTO_SUBFRAME;
   EXPECT_TRUE(controller.RendererDidNavigate(main_test_rfh(), params,
                                              &details));
   EXPECT_EQ(1U, navigation_entry_committed_counter_);
   navigation_entry_committed_counter_ = 0;
   EXPECT_EQ(3, controller.GetEntryCount());
   EXPECT_EQ(1, controller.GetCurrentEntryIndex());
   EXPECT_EQ(-1, controller.GetPendingEntryIndex());
   EXPECT_FALSE(controller.GetPendingEntry());
 
   // Go back one more.
   controller.GoBack();
+  params.page_id = 0;
   params.url = url1;
-  params.page_id = 0;
+  params.transition = ui::PAGE_TRANSITION_AUTO_SUBFRAME;
   EXPECT_TRUE(controller.RendererDidNavigate(main_test_rfh(), params,
                                              &details));
   EXPECT_EQ(1U, navigation_entry_committed_counter_);
   navigation_entry_committed_counter_ = 0;
   EXPECT_EQ(3, controller.GetEntryCount());
   EXPECT_EQ(0, controller.GetCurrentEntryIndex());
   EXPECT_EQ(-1, controller.GetPendingEntryIndex());
   EXPECT_FALSE(controller.GetPendingEntry());
 }
 
@@ skipping 2433 matching lines @@
   params.post_id = -1;
   contents()->GetMainFrame()->SendNavigateWithParams(&params);
 
   // Now reload. replaceState overrides the POST, so we should not show a
   // repost warning dialog.
   controller_impl().Reload(true);
   EXPECT_EQ(0, delegate->repost_form_warning_count());
 }
 
 }  // namespace content