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

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

Index: mojo/public/cpp/bindings/lib/bindings_serialization.cc
diff --git a/mojo/public/cpp/bindings/lib/bindings_serialization.cc b/mojo/public/cpp/bindings/lib/bindings_serialization.cc
index fc574d77e7ed5bce951a37dd3183c1aeb6d921e2..5e60c65a5c4b52e8e89a46b36ab368958d2c6696 100644
--- a/mojo/public/cpp/bindings/lib/bindings_serialization.cc
+++ b/mojo/public/cpp/bindings/lib/bindings_serialization.cc
@@ -11,9 +11,22 @@
 namespace mojo {
 namespace internal {
 
-size_t Align(size_t size) {
+namespace {
+
+template<typename T>
+T AlignImpl(T t) {
   const size_t kAlignment = 8;
-  return size + (kAlignment - (size % kAlignment)) % kAlignment;
+  return t + (kAlignment - (t % kAlignment)) % kAlignment;
+}
+
+}  // namespace
+
+size_t Align(size_t size) {
+  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) {