GN: Build app snapshots for the SDK tools.

runtime/bin/file_win.cc

Index: runtime/bin/file_win.cc
diff --git a/runtime/bin/file_win.cc b/runtime/bin/file_win.cc
index c9f98b560a1e375feea1684c6ed4bde87550611b..3e326c314561904db52862709dbabc2d8205a6e0 100644
--- a/runtime/bin/file_win.cc
+++ b/runtime/bin/file_win.cc
@@ -75,8 +75,24 @@ bool File::IsClosed() {
 
 
 void* File::Map(MapType type, int64_t position, int64_t length) {
-  UNIMPLEMENTED();
-  return NULL;
+  ASSERT(handle_->fd() >= 0);
+  int flags;
+  switch (type) {
+    case kReadOnly:
+      flags = PAGE_READONLY;
+      break;
+    case KReadExecute:
+      flags = PAGE_EXECUTE_READ:
+      break;
+    default:
+      return NULL;
+  }
+  HANDLE mapping = CreateFileMapping(handle_->fd(), NULL, flags, 0, 0, NULL);
+  return MapViewOfFile(mapping,
+                       FILE_MAP_READ,
+                       Utils::High32Bits(position),
+                       Utils::Low32Bits(position),
+                       length);
 }