Cleanup env variable names

fpdfsdk/cfx_systemhandler.h

Index: fpdfsdk/cfx_systemhandler.h
diff --git a/fpdfsdk/cfx_systemhandler.h b/fpdfsdk/cfx_systemhandler.h
index 9381d9e08c83b213e3c200a8a5412f14b6f14a6a..82cfc531ca2be804ffd86ec9e5f9e8b063823f2e 100644
--- a/fpdfsdk/cfx_systemhandler.h
+++ b/fpdfsdk/cfx_systemhandler.h
@@ -49,8 +49,8 @@ class CPDFSDK_Widget;
 
 class CFX_SystemHandler {
  public:
-  explicit CFX_SystemHandler(CPDFSDK_FormFillEnvironment* pEnv)
-      : m_pEnv(pEnv) {}
+  explicit CFX_SystemHandler(CPDFSDK_FormFillEnvironment* pFormFillEnv)
+      : m_pFormFillEnv(pFormFillEnv) {}
   ~CFX_SystemHandler() {}
 
   void InvalidateRect(CPDFSDK_Widget* widget, FX_RECT rect);
@@ -72,7 +72,7 @@ class CFX_SystemHandler {
   bool IsALTKeyDown(uint32_t nFlag) const;
 
  private:
-  CPDFSDK_FormFillEnvironment* const m_pEnv;
+  CPDFSDK_FormFillEnvironment* const m_pFormFillEnv;
 };
 
 #endif  // FPDFSDK_CFX_SYSTEMHANDLER_H_