Fixing remaining VC++ 2015 64-bit build breaks

base/win/win_util.h

Index: base/win/win_util.h
diff --git a/base/win/win_util.h b/base/win/win_util.h
index 384db80567bf6d319df487fabae6948ce5aeb93f..c1249d9126d53ef90dff45574c478cfbfe03a25f 100644
--- a/base/win/win_util.h
+++ b/base/win/win_util.h
@@ -56,6 +56,14 @@ struct NONCLIENTMETRICS_XP {
 namespace base {
 namespace win {
 
+inline uint32_t HandleToUint32(HANDLE h) {
+  // Cast through uintptr_t and then unsigned int to make the truncation to
+  // 32 bits explicit. Handles are size of-pointer but are always 32-bit values.
+  // https://msdn.microsoft.com/en-us/library/aa384203(VS.85).aspx says:
+  // 64-bit versions of Windows use 32-bit handles for interoperability.
+  return static_cast<uint32_t>(reinterpret_cast<uintptr_t>(h));
+}
+
 BASE_EXPORT void GetNonClientMetrics(NONCLIENTMETRICS_XP* metrics);
 
 // Returns the string representing the current user sid.