Mojo: Require our public options structs to be aligned like int64_t's.

mojo/public/c/system/data_pipe.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/constants and functions specific to data pipes.
 //
 // Note: This header should be compilable as C.
 
 #ifndef MOJO_PUBLIC_C_SYSTEM_DATA_PIPE_H_
 #define MOJO_PUBLIC_C_SYSTEM_DATA_PIPE_H_
@@ skipping 28 matching lines @@
     MOJO_CREATE_DATA_PIPE_OPTIONS_FLAG_NONE = 0;
 const MojoCreateDataPipeOptionsFlags
     MOJO_CREATE_DATA_PIPE_OPTIONS_FLAG_MAY_DISCARD = 1 << 0;
 #else
 #define MOJO_CREATE_DATA_PIPE_OPTIONS_FLAG_NONE \
     ((MojoCreateDataPipeOptionsFlags) 0)
 #define MOJO_CREATE_DATA_PIPE_OPTIONS_FLAG_MAY_DISCARD \
     ((MojoCreateDataPipeOptionsFlags) 1 << 0)
 #endif
 
-struct MojoCreateDataPipeOptions {
+MOJO_COMPILE_ASSERT(MOJO_ALIGNOF(int64_t) == 8, int64_t_has_weird_alignment);
+struct MOJO_ALIGNAS(8) MojoCreateDataPipeOptions {
   uint32_t struct_size;
   MojoCreateDataPipeOptionsFlags flags;
   uint32_t element_num_bytes;
   uint32_t capacity_num_bytes;
 };
 MOJO_COMPILE_ASSERT(sizeof(MojoCreateDataPipeOptions) == 16,
                     MojoCreateDataPipeOptions_has_wrong_size);
 
 // |MojoWriteDataFlags|: Used to specify different modes to |MojoWriteData()|
 // and |MojoBeginWriteData()|.
@@ skipping 296 matching lines @@
 //       |MojoEndReadData()| has already been called).
 MOJO_SYSTEM_EXPORT MojoResult MojoEndReadData(
     MojoHandle data_pipe_consumer_handle,
     uint32_t num_bytes_read);
 
 #ifdef __cplusplus
 }  // extern "C"
 #endif
 
 #endif  // MOJO_PUBLIC_C_SYSTEM_DATA_PIPE_H_