Implement support for loading font files from outside system directory

content/browser/renderer_host/dwrite_font_proxy_message_filter_win.h

Index: content/browser/renderer_host/dwrite_font_proxy_message_filter_win.h
diff --git a/content/browser/renderer_host/dwrite_font_proxy_message_filter_win.h b/content/browser/renderer_host/dwrite_font_proxy_message_filter_win.h
index 7539ff16f6b4a9a22b48b0a4a944747efa672f99..03be0fbf7dce0891396dffeb48df694384071245 100644
--- a/content/browser/renderer_host/dwrite_font_proxy_message_filter_win.h
+++ b/content/browser/renderer_host/dwrite_font_proxy_message_filter_win.h
@@ -37,6 +37,8 @@ class CONTENT_EXPORT DWriteFontProxyMessageFilter
   void OverrideThreadForMessage(const IPC::Message& message,
                                 content::BrowserThread::ID* thread) override;
 
+  void SetWindowsFontsPathForTesting(base::string16 path);
+
  protected:
   ~DWriteFontProxyMessageFilter() override;
 
@@ -46,7 +48,8 @@ class CONTENT_EXPORT DWriteFontProxyMessageFilter
       UINT32 family_index,
       std::vector<std::pair<base::string16, base::string16>>* family_names);
   void OnGetFontFiles(UINT32 family_index,
-                      std::vector<base::string16>* file_paths);
+                      std::vector<base::string16>* file_paths,
+                      std::vector<uint32_t>* file_handles);
   void OnMapCharacters(const base::string16& text,
                        const DWriteFontStyle& font_style,
                        const base::string16& locale_name,
@@ -57,10 +60,14 @@ class CONTENT_EXPORT DWriteFontProxyMessageFilter
   void InitializeDirectWrite();
 
  private:
-  bool AddFilesForFont(std::set<base::string16>* path_set, IDWriteFont* font);
+  bool AddFilesForFont(std::set<base::string16>* path_set,
+                       std::set<base::string16>* custom_font_path_set,
+                       IDWriteFont* font);
   bool AddLocalFile(std::set<base::string16>* path_set,
+                    std::set<base::string16>* custom_font_path_set,
                     IDWriteLocalFontFileLoader* local_loader,
                     IDWriteFontFile* font_file);
+  HANDLE CreateRendererHandleForPath(const base::string16& path);
 
   bool IsLastResortFallbackFont(uint32_t font_index);