Fix for the font files being maped multiple times (Fontconfig).

content/common/font_config_ipc_linux.h

Index: content/common/font_config_ipc_linux.h
diff --git a/content/common/font_config_ipc_linux.h b/content/common/font_config_ipc_linux.h
index 17082867986949f13ddf03f1d297ca5475f8694b..cbdabbeb1c9493358e70d696aefbc1f05a940989 100644
--- a/content/common/font_config_ipc_linux.h
+++ b/content/common/font_config_ipc_linux.h
@@ -6,6 +6,8 @@
 #define CONTENT_COMMON_FONT_CONFIG_IPC_LINUX_H_
 
 #include "base/compiler_specific.h"
+#include "base/containers/hash_tables.h"
+#include "base/synchronization/lock.h"
 #include "third_party/skia/include/core/SkStream.h"
 #include "third_party/skia/include/core/SkTypeface.h"
 #include "third_party/skia/include/ports/SkFontConfigInterface.h"
@@ -41,7 +43,18 @@ class FontConfigIPC : public SkFontConfigInterface {
   };
 
  private:
+  class MappedFontFile;
+
+  // Removes |mapped_font_file| from |mapped_font_files_|.
+  // Does not delete the passed-in object.
+  void RemoveMappedFontFile(MappedFontFile* mapped_font_file);
+
   const int fd_;
+  // Lock preventing multiple threads from opening font file and accessing
+  // |mapped_font_files_| map at the same time.
+  base::Lock lock_;
+  // Maps font identity ID to the memory-mapped file with font data.
+  base::hash_map<uint32_t, MappedFontFile*> mapped_font_files_;
 };
 
 }  // namespace content