[date] Refactor TimezoneCache to be separate from the OS

src/base/platform/platform-aix.cc

Index: src/base/platform/platform-aix.cc
diff --git a/src/base/platform/platform-aix.cc b/src/base/platform/platform-aix.cc
index 6d6adfb2cb1b19020921dbe5dde30d286bb4fe10..d659dadedd214eeb9220662b283f185e2044de74 100644
--- a/src/base/platform/platform-aix.cc
+++ b/src/base/platform/platform-aix.cc
@@ -29,9 +29,9 @@
 #undef MAP_TYPE
 
 #include "src/base/macros.h"
+#include "src/base/platform/platform-posix.h"
 #include "src/base/platform/platform.h"
 
-
 namespace v8 {
 namespace base {
 
@@ -42,8 +42,15 @@ static inline void* mmapHelper(size_t len, int prot, int flags, int fildes,
   return mmap(addr, len, prot, flags, fildes, off);
 }
 
+class AIXTimezoneCache : public PosixTimezoneCache {
+  const char* LocalTimezone(double time) override;
+
+  double LocalTimeOffset() override;
 
-const char* OS::LocalTimezone(double time, TimezoneCache* cache) {
+  ~AIXTimezoneCache() override {}
+};
+
+const char* AIXTimezoneCache::LocalTimezone(double time) {
   if (std::isnan(time)) return "";
   time_t tv = static_cast<time_t>(floor(time / msPerSecond));
   struct tm tm;
@@ -52,8 +59,7 @@ const char* OS::LocalTimezone(double time, TimezoneCache* cache) {
   return tzname[0];  // The location of the timezone string on AIX.
 }
 
-
-double OS::LocalTimeOffset(TimezoneCache* cache) {
+double AIXTimezoneCache::LocalTimeOffset() {
   // On AIX, struct tm does not contain a tm_gmtoff field.
   time_t utc = time(NULL);
   DCHECK(utc != -1);
@@ -63,6 +69,7 @@ double OS::LocalTimeOffset(TimezoneCache* cache) {
   return static_cast<double>((mktime(loc) - utc) * msPerSecond);
 }
 
+TimezoneCache* OS::CreateTimezoneCache() { return new AIXTimezoneCache(); }
 
 void* OS::Allocate(const size_t requested, size_t* allocated, bool executable) {
   const size_t msize = RoundUp(requested, getpagesize());