Make sure that ScratchBuffer::Allocate() always return 8-byte aligned address.

mojo/public/cpp/bindings/lib/bindings_serialization.h

 // Copyright 2013 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_BINDINGS_LIB_BINDINGS_SERIALIZATION_H_
 #define MOJO_PUBLIC_CPP_BINDINGS_LIB_BINDINGS_SERIALIZATION_H_
 
 #include <vector>
 
 #include "mojo/public/cpp/bindings/buffer.h"
 #include "mojo/public/cpp/bindings/message.h"
 
 namespace mojo {
 namespace internal {
 
 size_t Align(size_t size);
+char* AlignPointer(char* ptr);
 
 // Pointers are encoded as relative offsets. The offsets are relative to the
 // address of where the offset value is stored, such that the pointer may be
 // recovered with the expression:
 //
 //   ptr = reinterpret_cast<char*>(offset) + *offset
 //
 // A null pointer is encoded as an offset value of 0.
 //
 void EncodePointer(const void* ptr, uint64_t* offset);
@@ skipping 31 matching lines @@
     if (!obj->ptr->DecodePointersAndHandles(message))
       return false;
   }
   return true;
 }
 
 }  // namespace internal
 }  // namespace mojo
 
 #endif  // MOJO_PUBLIC_CPP_BINDINGS_LIB_BINDINGS_SERIALIZATION_H_