Add (optional) options to Run[Main]Application().

mojo/public/cpp/application/run_application.h

 // Copyright 2016 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_APPLICATION_RUN_APPLICATION_H_
 #define MOJO_PUBLIC_CPP_APPLICATION_RUN_APPLICATION_H_
 
 #include "mojo/public/c/system/handle.h"
 #include "mojo/public/c/system/result.h"
 
 namespace mojo {
 
 class ApplicationImplBase;
 
+// Base class for options to |RunMainApplication()| and |RunApplication()|. An
+// implementation of these functions may (but need not, in which case no options
+// are available) separately provide an implementation subclass, which would be
+// specific to that implementation. (The "standalone" implementation has no
+// options.)
+class RunApplicationOptions {
+ protected:
+  RunApplicationOptions() {}
+  ~RunApplicationOptions() {}
+};
+
 // |RunMainApplication()| and |RunApplication()| set up a message (run) loop and
 // run the provided application implementation. |RunMainApplication()| should be
 // used on the application's main thread (e.g., from |MojoMain()|) and may do
 // additional initialization. (In the case of the "standalone" implementation,
 // the two are equivalent.) The return value will be the one provided to
 // |TerminateMainApplication()| or |TerminateApplication()|, respectively.
 //
 // Typical use (where |MyApplicationImpl| is an implementation of
 // |ApplicationImplBase|):
 //
 //   MojoResult MojoMain(MojoHandle application_request_handle) {
 //     MyApplicationImpl my_app;
 //     return mojo::RunMainApplication(application_request_handle, &my_app);
 //   }
 //
 // |RunApplication()| may be used on secondary threads (that are not already
 // running a message loop of some sort).
 //
 // |*application_impl| must remain alive until the message loop starts running
-// (thus it may own itself).
+// (thus it may own itself). If |options| is non-null, then it must point to an
+// instance of an implementation-specific subclass of |RunApplicationOptions|;
+// |*options| must remain alive for the duration of the call.
 MojoResult RunMainApplication(MojoHandle application_request_handle,
-                              ApplicationImplBase* application_impl);
+                              ApplicationImplBase* application_impl,
+                              const RunApplicationOptions* options = nullptr);
 MojoResult RunApplication(MojoHandle application_request_handle,
-                          ApplicationImplBase* application_impl);
+                          ApplicationImplBase* application_impl,
+                          const RunApplicationOptions* options = nullptr);
 
 // |TerminateMainApplication()| and |TerminateApplication()| terminate the
 // application that is running on the current thread. They may only be called
 // from "inside" |RunMainApplication()| and |RunApplication()| respectively
 // (i.e., |Run[Main]Application()| is on the stack, which means that the message
 // loop is running). They will cause |Run[Main]Application()| to return "soon"
 // (assuming the message loop is not blocked processing some task), with return
 // value |result|. They may cause queued work to *not* be executed. They should
 // be executed at most once (per |Run[Main]Application()|).
 void TerminateMainApplication(MojoResult result);
 void TerminateApplication(MojoResult result);
 
 }  // namespace mojo
 
 #endif  // MOJO_PUBLIC_CPP_APPLICATION_RUN_APPLICATION_H_