Add abstractions that let embedders drive tests of WebContents.

chrome/test/base/chrome_render_view_host_test_harness.h

Index: chrome/test/base/chrome_render_view_host_test_harness.h
diff --git a/chrome/test/base/chrome_render_view_host_test_harness.h b/chrome/test/base/chrome_render_view_host_test_harness.h
index 10a5ca445cd2117d1099c399322be7ea38cfaa28..f8d15f532fb67b5c22c648a84215475112ae804a 100644
--- a/chrome/test/base/chrome_render_view_host_test_harness.h
+++ b/chrome/test/base/chrome_render_view_host_test_harness.h
@@ -11,6 +11,10 @@
 
 class TestingProfile;
 
+namespace content {
+class WebContents;
+}
+
 // Wrapper around RenderViewHostTestHarness that uses a TestingProfile as
 // browser context instead of a TestBrowserContext.
 class ChromeRenderViewHostTestHarness : public RenderViewHostTestHarness {
@@ -20,6 +24,7 @@ class ChromeRenderViewHostTestHarness : public RenderViewHostTestHarness {
 
   TestingProfile* profile();
 
+  content::WebContents* contents();
   content::RenderViewHostTester* rvh_tester();
 
  protected: