Don't swap out the old RenderFrameHost until the new one commits.

content/renderer/render_view_browsertest.cc

Index: content/renderer/render_view_browsertest.cc
diff --git a/content/renderer/render_view_browsertest.cc b/content/renderer/render_view_browsertest.cc
index 7b57cf7826dde757b7db2c7f55bcd80c86ad5f9b..6b8232db120b2e3699b59ed93f8aec762391c925 100644
--- a/content/renderer/render_view_browsertest.cc
+++ b/content/renderer/render_view_browsertest.cc
@@ -33,6 +33,7 @@
 #include "content/renderer/accessibility/renderer_accessibility_focus_only.h"
 #include "content/renderer/history_controller.h"
 #include "content/renderer/history_serialization.h"
+#include "content/renderer/render_process.h"
 #include "content/renderer/render_view_impl.h"
 #include "content/shell/browser/shell.h"
 #include "content/shell/browser/shell_browser_context.h"
@@ -497,6 +498,9 @@ TEST_F(RenderViewImplTest, SendSwapOutACK) {
   LoadHTML("<div>Page A</div>");
   int initial_page_id = view_page_id();
 
+  // Increment the ref count so that we don't exit when swapping out.
+  RenderProcess::current()->AddRefProcess();
+
   // Respond to a swap out request.
   view()->main_render_frame()->OnSwapOut(kProxyRoutingId);