Switch the background color in PDF Viewer when using Material Design

pdf/pdfium/pdfium_engine.h

Index: pdf/pdfium/pdfium_engine.h
diff --git a/pdf/pdfium/pdfium_engine.h b/pdf/pdfium/pdfium_engine.h
index d7b48355666c4fddb257b85e22d19065e89b5ff9..331d37b95ac06b44982d2039c09347a3d7194b73 100644
--- a/pdf/pdfium/pdfium_engine.h
+++ b/pdf/pdfium/pdfium_engine.h
@@ -80,6 +80,8 @@ class PDFiumEngine : public PDFEngine,
   virtual bool HasPermission(DocumentPermission permission) const;
   virtual void SelectAll();
   virtual int GetNumberOfPages();
+  virtual uint32 GetBackgroundColor();
+  virtual void SetBackgroundColor(uint32 backgroundColor);
   virtual pp::VarArray GetBookmarks();
   virtual int GetNamedDestinationPage(const std::string& destination);
   virtual pp::VarDictionary GetNamedDestinations();
@@ -681,6 +683,9 @@ class PDFiumEngine : public PDFEngine,
   // Whether to render in grayscale or in color.
   bool render_grayscale_;
 
+  // Background color of the PDF.
+  uint32 background_color_;
+
   // The link currently under the cursor.
   std::string link_under_cursor_;