Move existing kSitePerProcess checks to a policy-oracle object

content/browser/web_contents/web_contents_impl_unittest.cc

Index: content/browser/web_contents/web_contents_impl_unittest.cc
diff --git a/content/browser/web_contents/web_contents_impl_unittest.cc b/content/browser/web_contents/web_contents_impl_unittest.cc
index d2300e9db266072b6d37bcc59931adedd5d47210..380e4f27e50160e864d78b230259be1dd9fdcea3 100644
--- a/content/browser/web_contents/web_contents_impl_unittest.cc
+++ b/content/browser/web_contents/web_contents_impl_unittest.cc
@@ -32,6 +32,7 @@
 #include "content/public/common/content_switches.h"
 #include "content/public/common/url_constants.h"
 #include "content/public/common/url_utils.h"
+#include "content/public/test/browser_test_utils.h"
 #include "content/public/test/mock_render_process_host.h"
 #include "content/public/test/test_utils.h"
 #include "content/test/test_content_browser_client.h"
@@ -2886,8 +2887,7 @@ TEST_F(WebContentsImplTest, StartStopEventsBalance) {
   // The bug manifests itself in regular mode as well, but browser-initiated
   // navigation of subframes is only possible in --site-per-process mode within
   // unit tests.
-  base::CommandLine::ForCurrentProcess()->AppendSwitch(
-      switches::kSitePerProcess);
+  IsolateAllSitesForTesting(base::CommandLine::ForCurrentProcess());
   const GURL initial_url("about:blank");
   const GURL main_url("http://www.chromium.org");
   const GURL foo_url("http://foo.chromium.org");