Add font substitution metric for Linux

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 102 matching lines @@
 
   // DocumentLoader::Client implementation.
   pp::Instance* GetPluginInstance() override;
   pp::URLLoader CreateURLLoader() override;
   void OnPartialDocumentLoaded() override;
   void OnPendingRequestComplete() override;
   void OnNewDataAvailable() override;
   void OnDocumentComplete() override;
 
   void UnsupportedFeature(int type);
+  void FontSubstituted();
 
   std::string current_find_text() const { return current_find_text_; }
 
   FPDF_DOCUMENT doc() { return doc_; }
   FPDF_FORMHANDLE form() { return form_; }
 
  private:
   // This helper class is used to detect the difference in selection between
   // construction and destruction.  At destruction, it invalidates all the
   // parts that are newly selected, along with all the parts that used to be
@@ skipping 602 matching lines @@
 
 // Create a local variable of this when calling PDFium functions which can call
 // our global callback when an unsupported feature is reached.
 class ScopedUnsupportedFeature {
  public:
   explicit ScopedUnsupportedFeature(PDFiumEngine* engine);
   ~ScopedUnsupportedFeature();
 
  private:
   PDFiumEngine* const old_engine_;
+
+  DISALLOW_COPY_AND_ASSIGN(ScopedUnsupportedFeature);
+};
+
+// Create a local variable of this when calling PDFium functions which can call
+// our global callback when a substitute font is mapped.
+class ScopedSubstFont {
+ public:
+  explicit ScopedSubstFont(PDFiumEngine* engine);
+  ~ScopedSubstFont();
+
+ private:
+  PDFiumEngine* const old_engine_;
+
+  DISALLOW_COPY_AND_ASSIGN(ScopedSubstFont);
 };
 
 class PDFiumEngineExports : public PDFEngineExports {
  public:
   PDFiumEngineExports() {}
 
 // PDFEngineExports:
 #if defined(OS_WIN)
   bool RenderPDFPageToDC(const void* pdf_buffer,
                          int buffer_size,
@@ skipping 17 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_