Use override in more classes in core/

core/src/fxge/android/fpf_skiamodule.h

 // Copyright 2014 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
 
 #ifndef CORE_SRC_FXGE_ANDROID_FPF_SKIAMODULE_H_
 #define CORE_SRC_FXGE_ANDROID_FPF_SKIAMODULE_H_
 
 #if _FX_OS_ == _FX_ANDROID_
+
+#include "../../../include/fxge/fpf.h"
+
 class CFPF_SkiaFontMgr;
+
 class CFPF_SkiaDeviceModule : public IFPF_DeviceModule {
  public:
-  CFPF_SkiaDeviceModule() : m_pFontMgr(NULL) {}
-  virtual ~CFPF_SkiaDeviceModule();
-  virtual void Destroy();
-  virtual IFPF_FontMgr* GetFontMgr();
+  CFPF_SkiaDeviceModule() : m_pFontMgr(nullptr) {}
+  ~CFPF_SkiaDeviceModule() override;
+
+  // IFPF_DeviceModule
+  void Destroy() override;
+  IFPF_FontMgr* GetFontMgr() override;
 
  protected:
   CFPF_SkiaFontMgr* m_pFontMgr;
 };
 #endif
 
 #endif  // CORE_SRC_FXGE_ANDROID_FPF_SKIAMODULE_H_