Turn on enforce-in-pdf Clang plugin flag.

pdf/pdfium/pdfium_engine.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef PDF_PDFIUM_PDFIUM_ENGINE_H_
 #define PDF_PDFIUM_PDFIUM_ENGINE_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 69 matching lines @@
   bool HasPermission(DocumentPermission permission) const override;
   void SelectAll() override;
   int GetNumberOfPages() override;
   pp::VarArray GetBookmarks() override;
   int GetNamedDestinationPage(const std::string& destination) override;
   int GetMostVisiblePage() override;
   pp::Rect GetPageRect(int index) override;
   pp::Rect GetPageBoundsRect(int index) override;
   pp::Rect GetPageContentsRect(int index) override;
   pp::Rect GetPageScreenRect(int page_index) const override;
-  int GetVerticalScrollbarYPosition() override { return position_.y(); }
+  int GetVerticalScrollbarYPosition() override;
   void SetGrayscale(bool grayscale) override;
   void OnCallback(int id) override;
   int GetCharCount(int page_index) override;
   pp::FloatRect GetCharBounds(int page_index, int char_index) override;
   uint32_t GetCharUnicode(int page_index, int char_index) override;
   void GetTextRunInfo(int page_index,
                       int start_char_index,
                       uint32_t* out_len,
                       double* out_font_size,
                       pp::FloatRect* out_bounds) override;
@@ skipping 654 matching lines @@
   bool GetPDFPageSizeByIndex(const void* pdf_buffer,
                              int pdf_buffer_size,
                              int page_number,
                              double* width,
                              double* height) override;
 };
 
 }  // namespace chrome_pdf
 
 #endif  // PDF_PDFIUM_PDFIUM_ENGINE_H_