Make chrome_elf use thunks instead of function pointers.

sandbox/win/src/service_resolver_64.cc

Index: sandbox/win/src/service_resolver_64.cc
diff --git a/sandbox/win/src/service_resolver_64.cc b/sandbox/win/src/service_resolver_64.cc
index 96124187deb4b383708bca09645f81f3bced75f9..79c6b16ebef7c540462d80697f29ffac4548a2c7 100644
--- a/sandbox/win/src/service_resolver_64.cc
+++ b/sandbox/win/src/service_resolver_64.cc
@@ -116,6 +116,30 @@ size_t ServiceResolverThunk::GetThunkSize() const {
   return sizeof(ServiceFullThunk);
 }
 
+NTSTATUS ServiceResolverThunk::CopyThunk(const void* target_module,
+                                         const char* target_name,
+                                         BYTE* thunk_storage,
+                                         size_t storage_bytes,
+                                         size_t* storage_used) {
+  NTSTATUS ret = ResolveTarget(target_module, target_name, &target_);
+  if (!NT_SUCCESS(ret))
+    return ret;
+
+  size_t thunk_bytes = GetThunkSize();
+  if (storage_bytes < thunk_bytes)
+    return STATUS_UNSUCCESSFUL;
+
+  ServiceFullThunk* thunk = reinterpret_cast<ServiceFullThunk*>(thunk_storage);
+
+  if (!IsFunctionAService(&thunk->original))
+    return STATUS_UNSUCCESSFUL;
+
+  if (NULL != storage_used)
+    *storage_used = thunk_bytes;
+
+  return ret;
+}
+
 bool ServiceResolverThunk::IsFunctionAService(void* local_thunk) const {
   ServiceFullThunk function_code;
   SIZE_T read;