Fixed test by changing the way a subframe was added.

content/browser/frame_host/navigator_impl_unittest.cc

 // Copyright 2014 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/command_line.h"
 #include "base/macros.h"
 #include "base/time/time.h"
 #include "content/browser/frame_host/navigation_controller_impl.h"
 #include "content/browser/frame_host/navigation_entry_impl.h"
 #include "content/browser/frame_host/navigation_request.h"
@@ skipping 115 matching lines @@
 // flag kEnableBrowserSideNavigation.
 TEST_F(NavigatorTestWithBrowserSideNavigation, BeginNavigation) {
   const GURL kUrl1("http://www.google.com/");
   const GURL kUrl2("http://www.chromium.org/");
   const GURL kUrl3("http://www.gmail.com/");
 
   contents()->NavigateAndCommit(kUrl1);
 
   // Add a subframe.
   FrameTreeNode* root_node = contents()->GetFrameTree()->root();
-  TestRenderFrameHost* subframe_rfh =
-      static_cast<TestRenderFrameHost*>(contents()->GetFrameTree()->AddFrame(
-          root_node, root_node->current_frame_host()->GetProcess()->GetID(), 14,
-          "Child"));
+  TestRenderFrameHost* subframe_rfh = main_test_rfh()->AppendChild("Child");
   ASSERT_TRUE(subframe_rfh);
 
   FrameTreeNode* subframe_node = subframe_rfh->frame_tree_node();
   SendRequestNavigation(subframe_node, kUrl2);
   // There is no previous renderer in the subframe, so BeginNavigation is
   // handled already.
   NavigationRequest* subframe_request =
       GetNavigationRequestForFrameTreeNode(subframe_node);
   TestNavigationURLLoader* subframe_loader =
       GetLoaderForNavigationRequest(subframe_request);
@@ skipping 487 matching lines @@
   EXPECT_TRUE(DidRenderFrameHostRequestCommit(rfh1));
   EXPECT_FALSE(DidRenderFrameHostRequestCommit(main_test_rfh()));
 
   rfh1->SendNavigate(1, kUrl1);
   EXPECT_EQ(rfh1, main_test_rfh());
   EXPECT_EQ(RenderFrameHostImpl::STATE_DEFAULT, rfh1->rfh_state());
   EXPECT_FALSE(rfhm->IsOnSwappedOutList(rfh1));
 }
 
 }  // namespace content