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

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

 // 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.
 
 #include "mojo/public/cpp/bindings/lib/bindings_serialization.h"
 
 #include <assert.h>
 
 #include "mojo/public/cpp/bindings/lib/bindings_internal.h"
 
 namespace mojo {
 namespace internal {
 
+namespace {
+
+template<typename T>
+T AlignImpl(T t) {
+  const size_t kAlignment = 8;
+  return t + (kAlignment - (t % kAlignment)) % kAlignment;
+}
+
+}  // namespace
+
 size_t Align(size_t size) {
-  const size_t kAlignment = 8;
-  return size + (kAlignment - (size % kAlignment)) % kAlignment;
+  return AlignImpl(size);
+}
+
+char* AlignPointer(char* ptr) {
+  return reinterpret_cast<char*>(AlignImpl(reinterpret_cast<uintptr_t>(ptr)));
 }
 
 void EncodePointer(const void* ptr, uint64_t* offset) {
   if (!ptr) {
     *offset = 0;
     return;
   }
 
   const char* p_obj = reinterpret_cast<const char*>(ptr);
   const char* p_slot = reinterpret_cast<const char*>(offset);
@@ skipping 37 matching lines @@
   }
   if (handle->value() >= handles->size())
     return false;
   // Just leave holes in the vector so we don't screw up other indices.
   *handle = FetchAndReset(&handles->at(handle->value()));
   return true;
 }
 
 }  // namespace internal
 }  // namespace mojo