Add implementations of mojo::{Run,Terminate}[Main]Application() for "chromium".

mojo/public/cpp/application/lib/run_application.cc

Index: mojo/public/cpp/application/lib/run_application.cc
diff --git a/mojo/public/cpp/application/lib/run_application.cc b/mojo/public/cpp/application/lib/run_application.cc
index 4ca4a1a4c435be8d7f087a7c1d8578a1e3ce5ae7..e34d245274639fbca39ac1f868cabae3257ab065 100644
--- a/mojo/public/cpp/application/lib/run_application.cc
+++ b/mojo/public/cpp/application/lib/run_application.cc
@@ -25,7 +25,9 @@ struct ResultHolder {
 #ifndef NDEBUG
   bool is_set = false;
 #endif
-  MojoResult result = MOJO_RESULT_UNKNOWN;
+  // TODO(vtl): The default result should probably be |MOJO_RESULT_UNKNOWN|, but
+  // |ApplicationRunner| always returned |MOJO_RESULT_OK|.
+  MojoResult result = MOJO_RESULT_OK;
 };
 
 pthread_key_t g_current_result_holder_key;