Mojo: Wrap the satisfied/unsatisfied wait flags state in a single object.

mojo/public/c/system/types.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.
 
 // This file contains types and constants/macros common to different Mojo system
 // APIs.
 //
 // Note: This header should be compilable as C.
 
 #ifndef MOJO_PUBLIC_C_SYSTEM_TYPES_H_
 #define MOJO_PUBLIC_C_SYSTEM_TYPES_H_
 
 #include <stdint.h>
 
+#include "mojo/public/c/system/macros.h"
+
 // TODO(vtl): Notes: Use of undefined flags will lead to undefined behavior
 // (typically they'll be ignored), not necessarily an error.
 
 // |MojoTimeTicks|: Used to specify time ticks. Value is in microseconds.
 
 typedef int64_t MojoTimeTicks;
 
 // |MojoHandle|: Handles to Mojo objects.
 //   |MOJO_HANDLE_INVALID| - A value that is never a valid handle.
 
@@ skipping 130 matching lines @@
 const MojoWaitFlags MOJO_WAIT_FLAG_READABLE = 1 << 0;
 const MojoWaitFlags MOJO_WAIT_FLAG_WRITABLE = 1 << 1;
 const MojoWaitFlags MOJO_WAIT_FLAG_EVERYTHING = ~0;
 #else
 #define MOJO_WAIT_FLAG_NONE ((MojoWaitFlags) 0)
 #define MOJO_WAIT_FLAG_READABLE ((MojoWaitFlags) 1 << 0)
 #define MOJO_WAIT_FLAG_WRITABLE ((MojoWaitFlags) 1 << 1)
 #define MOJO_WAIT_FLAG_EVERYTHING (~((MojoWaitFlags) 0))
 #endif
 
+// TODO(vtl): Add out parameters with this to MojoWait/MojoWaitMany.
+// Note: This struct is not extensible (and only has 32-bit quantities), so it's
+// 32-bit-aligned.
+MOJO_COMPILE_ASSERT(MOJO_ALIGNOF(int32_t) == 4, int32_t_has_weird_alignment);
+struct MOJO_ALIGNAS(4) MojoWaitFlagsState {
+  MojoWaitFlags satisfied_flags;
+  MojoWaitFlags satisfiable_flags;
+};
+MOJO_COMPILE_ASSERT(sizeof(MojoWaitFlagsState) == 8,
+                    MojoWaitFlagsState_has_wrong_size);
+
 #endif  // MOJO_PUBLIC_C_SYSTEM_TYPES_H_