Simplify mojo_shell since it's now only used for Mandoline.

mojo/application/application_test_main_chromium.cc

Index: mojo/application/application_test_main_chromium.cc
diff --git a/mojo/application/application_test_main_chromium.cc b/mojo/application/application_test_main_chromium.cc
index 4ce761a8a36ffa7a741c862cc82623a30a6f2c7e..3d6c4b2ccc687592d67f8d02e87d5f55bcd7cebb 100644
--- a/mojo/application/application_test_main_chromium.cc
+++ b/mojo/application/application_test_main_chromium.cc
@@ -5,8 +5,9 @@
 #include "base/at_exit.h"
 #include "base/command_line.h"
 #include "base/test/test_timeouts.h"
+#include "mojo/application/application_runner_chromium.h"
+#include "mojo/application/application_test_base_chromium.h"
 #include "mojo/public/c/system/main.h"
-#include "mojo/public/cpp/application/application_test_base.h"
 
 MojoResult MojoMain(MojoHandle handle) {
   // An AtExitManager instance is needed to construct message loops.
@@ -14,7 +15,7 @@ MojoResult MojoMain(MojoHandle handle) {
 
   // Initialize test timeouts, which requires CommandLine::ForCurrentProcess().
   // TODO(msw): Plumb relevant command line args before initializing timeouts.
-  base::CommandLine::Init(0, nullptr);
+  mojo::ApplicationRunnerChromium::InitBaseCommandLine();
   TestTimeouts::Initialize();
 
   return mojo::test::RunAllTests(handle);