Change bool type to fix warnings.

fpdfsdk/cfx_systemhandler.cpp

 // Copyright 2016 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #include "fpdfsdk/cfx_systemhandler.h"
 
 #include "fpdfsdk/formfiller/cffl_formfiller.h"
 #include "fpdfsdk/include/fsdk_mgr.h"
@@ skipping 108 matching lines @@
 
 void CFX_SystemHandler::KillTimer(int32_t nID) {
   m_pEnv->FFI_KillTimer(nID);
 }
 
 FX_SYSTEMTIME CFX_SystemHandler::GetLocalTime() {
   return m_pEnv->FFI_GetLocalTime();
 }
 
 bool CFX_SystemHandler::IsSHIFTKeyDown(uint32_t nFlag) const {
-  return m_pEnv->FFI_IsSHIFTKeyDown(nFlag);
+  return !!m_pEnv->FFI_IsSHIFTKeyDown(nFlag);
 }
 
 bool CFX_SystemHandler::IsCTRLKeyDown(uint32_t nFlag) const {
-  return m_pEnv->FFI_IsCTRLKeyDown(nFlag);
+  return !!m_pEnv->FFI_IsCTRLKeyDown(nFlag);
 }
 
 bool CFX_SystemHandler::IsALTKeyDown(uint32_t nFlag) const {
-  return m_pEnv->FFI_IsALTKeyDown(nFlag);
+  return !!m_pEnv->FFI_IsALTKeyDown(nFlag);
 }
-
-bool CFX_SystemHandler::IsINSERTKeyDown(uint32_t nFlag) const {
-  return m_pEnv->FFI_IsINSERTKeyDown(nFlag);
-}