Initialize V8 in PDFium from external files (in-renderer process only).

gin/public/isolate_holder.h

Index: gin/public/isolate_holder.h
diff --git a/gin/public/isolate_holder.h b/gin/public/isolate_holder.h
index 4e14ade3fd45cab820fb7ddc464a99dd78b5a56b..18e07458cf24eb52de581e3b3d2aa2ac4ed35b86 100644
--- a/gin/public/isolate_holder.h
+++ b/gin/public/isolate_holder.h
@@ -56,6 +56,12 @@ class GIN_EXPORT IsolateHolder {
   static bool LoadV8SnapshotFD(int natives_fd, int snapshot_fd);
 #endif
   static bool LoadV8Snapshot();
+#ifndef OS_ANDROID
+  static void GetV8ExternalSnapshotData(const char** natives_data_out,
+                                        int* natives_size_out,
+                                        const char** snapshot_data_out,
+                                        int* snapshot_size_out);
+#endif  // OS_ANDROID
 #endif  // V8_USE_EXTERNAL_STARTUP_DATA
 
  private: