mojo: first take on removing mojo_main_{chromium,standalone}.

mojo/public/cpp/system/main.h

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef MOJO_PUBLIC_CPP_SYSTEM_MAIN_H_
+#define MOJO_PUBLIC_CPP_SYSTEM_MAIN_H_
+
+#include "mojo/public/cpp/system/core.h"
+
+#if defined(WIN32)

[viettrungluu, 2014/08/19 22:30:57]

I think I'd write this as

#if defined(WIN32)
extern "C" __declspec(dllexport) MojoResult __cdecl MojoMain(...);
#else
...
#endif

rather than having this header "export" a whole bunch of macros for no
particular reason.

But this really should be in the public/c/system. (See functions.h for the
conditionals around the |extern "C"| bits; it's fine/equivalent to declare this
using |extern "C" { ... }| instead -- but the |extern "C"| part should be
omitted if you're actually compiling as C.)

(Maybe it should be part of functions.h. You could also put it directly in
types.h. You can't put it in its own header[*] and have types.h include that,
due to a circular dependency.)

[*] Unless you did something evil like put the #include after the "body" of the
include file.

[tim (not reviewing), 2014/08/20 18:02:06]

Thanks for the explanation. I removed the extra exports and moved the
declaration to c/system. MojoMain still feels different to me than stuff in
functions.h/types.h/elsewhere, so I kept it in its own file...

I included it from core.h because core.h is already a catch-all for several
other files.

+#if !defined(CDECL)
+#define CDECL __cdecl
+#endif
+#define MOJO_MAIN_EXPORT __declspec(dllexport)
+#else
+#define CDECL
+#define MOJO_MAIN_EXPORT __attribute__((visibility("default")))
+#endif
+
+// DSOs should implement MojoMain directly. Note that the fancy decorations

[viettrungluu, 2014/08/19 22:30:57]

You shouldn't mention "DSOs", since the fact that anything is a DSO is a
platform-dependent detail. (E.g., on NaCl, it'd be "executable"/NEXE.)

[tim (not reviewing), 2014/08/20 18:02:06]

Noted. Done.

+// are not required in the definition, so you should write
+//
+// MojoResult MojoMain(MojoHandle shell_handle) {
+//   ...
+// }
+//
+// See public/cpp/application/application_runner* for recommended way of

[viettrungluu, 2014/08/19 22:30:57]

I think you can omit this comment. cpp/system doesn't recommend anything, and
doesn't favor our framework.

[tim (not reviewing), 2014/08/20 18:02:06]

OK, done.

+// launching an ApplicationImpl.
+// TODO(davemoore): Establish this as part of our SDK for third party mojo
+// application writers.
+extern "C" MOJO_MAIN_EXPORT MojoResult CDECL MojoMain(
+    MojoHandle service_provider_handle);
+
+#endif  // MOJO_PUBLIC_CPP_SYSTEM_MAIN_H_