Add abstractions that let embedders drive tests of WebContents.

content/browser/renderer_host/test_render_view_host.cc

 // Copyright (c) 2012 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/browser/renderer_host/test_backing_store.h"
 #include "content/browser/renderer_host/test_render_view_host.h"
 #include "content/browser/site_instance_impl.h"
 #include "content/browser/tab_contents/navigation_controller_impl.h"
 #include "content/browser/tab_contents/test_tab_contents.h"
 #include "content/common/dom_storage_common.h"
@@ skipping 301 matching lines @@
 }
 
 TestRenderViewHost* RenderViewHostImplTestHarness::pending_test_rvh() {
   return static_cast<TestRenderViewHost*>(pending_rvh());
 }
 
 TestRenderViewHost* RenderViewHostImplTestHarness::active_test_rvh() {
   return static_cast<TestRenderViewHost*>(active_rvh());
 }
 
+TestTabContents* RenderViewHostImplTestHarness::contents() {
+  return static_cast<TestTabContents*>(web_contents());
+}
+
 }  // namespace content