Use process/control messages (instead of RVH messages) for layout tests.

content/shell/app/shell_main_delegate.cc

Index: content/shell/app/shell_main_delegate.cc
diff --git a/content/shell/app/shell_main_delegate.cc b/content/shell/app/shell_main_delegate.cc
index 82fa47a6c47744758856ded07268799eee9f3377..2d494c150051b32180148198638904bcdb1b942c 100644
--- a/content/shell/app/shell_main_delegate.cc
+++ b/content/shell/app/shell_main_delegate.cc
@@ -26,9 +26,7 @@
 #include "content/shell/browser/layout_test/layout_test_content_browser_client.h"
 #include "content/shell/browser/shell_browser_main.h"
 #include "content/shell/browser/shell_content_browser_client.h"
-#include "content/shell/common/layout_test/layout_test_content_client.h"
 #include "content/shell/common/layout_test/layout_test_switches.h"
-#include "content/shell/common/shell_content_client.h"
 #include "content/shell/common/shell_switches.h"
 #include "content/shell/renderer/layout_test/layout_test_content_renderer_client.h"
 #include "content/shell/renderer/shell_content_renderer_client.h"
@@ -223,11 +221,7 @@ bool ShellMainDelegate::BasicStartupComplete(int* exit_code) {
     }
   }
 
-  content_client_.reset(base::CommandLine::ForCurrentProcess()->HasSwitch(
-                            switches::kRunLayoutTest)
-                            ? new LayoutTestContentClient
-                            : new ShellContentClient);
-  SetContentClient(content_client_.get());
+  SetContentClient(&content_client_);
 
   return false;
 }