Make FPDF_WIDESTRING work regardless of endianness.

testing/test_support.cpp

Index: testing/test_support.cpp
diff --git a/testing/test_support.cpp b/testing/test_support.cpp
index f71f6f8b4f6de6af2562c4269717b62ef0ded35d..c7ab10ee3cf2e8c3b15522e136728eca8b5042dc 100644
--- a/testing/test_support.cpp
+++ b/testing/test_support.cpp
@@ -98,7 +98,7 @@ char* GetFileContents(const char* filename, size_t* retlen) {
   return buffer;
 }
 
-std::wstring GetWideString(FPDF_WIDESTRING wstr) {
+std::wstring GetPlatformWString(FPDF_WIDESTRING wstr) {
   if (!wstr)
     return nullptr;
 
@@ -114,6 +114,19 @@ std::wstring GetWideString(FPDF_WIDESTRING wstr) {
   return platform_string;
 }
 
+FPDF_WIDESTRING GetFPDFWideString(const std::wstring& wstr) {
+  size_t length = sizeof(uint16_t) * (wstr.length() + 1);
+  unsigned char* ptr = static_cast<unsigned char*>(malloc(length));
+  size_t i = 0;
+  for (wchar_t w : wstr) {
+    ptr[i++] = w & 0xff;
+    ptr[i++] = (w >> 8) & 0xff;
+  }
+  ptr[i++] = 0;
+  ptr[i] = 0;
+  return reinterpret_cast<FPDF_WIDESTRING>(ptr);
+}
+
 #ifdef PDF_ENABLE_V8
 #ifdef V8_USE_EXTERNAL_STARTUP_DATA
 bool InitializeV8ForPDFium(const std::string& exe_path,