Observe all formfill environment pointer in JS objects.

Preventitve measure to decouple JS object lifetimes from C++
objects.

Change-Id: I964a52590fcd0bfc26ac6055a7daf8aa33d455f3
Reviewed-on: https://pdfium-review.googlesource.com/2828
Reviewed-by: dsinclair <dsinclair@chromium.org>
Commit-Queue: Tom Sepez <tsepez@chromium.org>
diff --git a/fpdfsdk/javascript/global.h b/fpdfsdk/javascript/global.h
index 50dfcf3..e313929 100644
--- a/fpdfsdk/javascript/global.h
+++ b/fpdfsdk/javascript/global.h
@@ -68,7 +68,7 @@
   std::map<CFX_ByteString, JSGlobalData*> m_mapGlobal;
   CFX_WideString m_sFilePath;
   CJS_GlobalData* m_pGlobalData;
-  CPDFSDK_FormFillEnvironment* m_pFormFillEnv;
+  CPDFSDK_FormFillEnvironment::ObservedPtr m_pFormFillEnv;
 };
 
 class CJS_Global : public CJS_Object {