Make Clipboard::FormatType an opaque handle type.

ui/base/clipboard/clipboard.h

Index: ui/base/clipboard/clipboard.h
diff --git a/ui/base/clipboard/clipboard.h b/ui/base/clipboard/clipboard.h
index 39cb5d4b27c4b79862fd93015d6d0eb5d2a5293a..9993423da45667dddd7b942aabc055381b0654a8 100644
--- a/ui/base/clipboard/clipboard.h
+++ b/ui/base/clipboard/clipboard.h
@@ -16,6 +16,10 @@
 #include "base/string16.h"
 #include "ui/base/ui_export.h"
 
+#if defined(TOOLKIT_USES_GTK)
+#include <gdk/gdk.h>
+#endif
+
 namespace gfx {
 class Size;
 }
@@ -27,11 +31,49 @@ class SkBitmap;
 typedef struct _GtkClipboard GtkClipboard;
 #endif
 
+#ifdef __OBJC__
+@class NSString;
+#else
+class NSString;
+#endif
+
 namespace ui {
 
 class UI_EXPORT Clipboard {
  public:
-  typedef std::string FormatType;
+  // Platform neutral holder for native data representation of a clipboard type.
+  struct UI_EXPORT FormatType {
+    // This only exists for the sake of IPC::Message serialization and
+    // deserialization.
+    FormatType();
+    ~FormatType();
+
+   private:
+    friend class Clipboard;
+
+#if defined(OS_WIN)
+    explicit FormatType(UINT native_format);
+    UINT data() const { return data_; }
+    UINT data_;
+#elif defined(USE_AURA)
+    explicit FormatType(const std::string& native_format);
+    const std::string& data() const { return data_; }
+    std::string data_;
+#elif defined(TOOLKIT_USES_GTK)
+    explicit FormatType(const std::string& native_format);
+    explicit FormatType(const GdkAtom& native_format);
+    const GdkAtom& data() const { return data_; }
+    GdkAtom data_;
+#elif defined(OS_MACOSX)
+    explicit FormatType(NSString* native_format);
+    NSString* data() const { return data_; }
+    // We don't use scoped_nsobject because this header gets included in a lot
+    // of places.
+    NSString* data_;
+#else
+#error No FormatType definition.
+#endif
+  };
 
   // ObjectType designates the type of data to be stored in the clipboard. This
   // designation is shared across all OSes. The system-specific designation
@@ -132,11 +174,6 @@ class UI_EXPORT Clipboard {
   // Tests whether the clipboard contains a certain format
   bool IsFormatAvailable(const FormatType& format, Buffer buffer) const;
 
-  // As above, but instead of interpreting |format| by some platform-specific
-  // definition, interpret it as a literal MIME type.
-  bool IsFormatAvailableByString(const std::string& format,
-                                 Buffer buffer) const;
-
   void ReadAvailableTypes(Buffer buffer, std::vector<string16>* types,
                           bool* contains_filenames) const;
 
@@ -170,23 +207,32 @@ class UI_EXPORT Clipboard {
 
   // Reads raw data from the clipboard with the given format type. Stores result
   // as a byte vector.
-  // TODO(dcheng): Due to platform limitations on Windows, we should make sure
-  // format is never controlled by the user.
-  void ReadData(const std::string& format, std::string* result) const;
-
-  // Get format Identifiers for various types.
-  static FormatType GetUrlFormatType();
-  static FormatType GetUrlWFormatType();
-  static FormatType GetMozUrlFormatType();
-  static FormatType GetPlainTextFormatType();
-  static FormatType GetPlainTextWFormatType();
-  static FormatType GetFilenameFormatType();
-  static FormatType GetFilenameWFormatType();
-  static FormatType GetWebKitSmartPasteFormatType();
+  void ReadData(const FormatType& format, std::string* result) const;
+
+  // Converts a format name into a FormatType, registering it with the system as
+  // needed. Due to Windows/Linux limitiations, |format_string| must never be
+  // controlled by the user.
+  static FormatType RegisterFormatType(const std::string& format_string);

[tony, 2011/12/06 18:58:29]

Nit: I would perhaps name this GetFormatType since it feels like registration is
a side effect of getting the format type rather than getting the format type a
side effect of registering.

[dcheng, 2011/12/06 22:57:02]

Done.

+
+  // Helpers to serialize/deserialize FormatType to strings. These probably do
+  // NOT do what you want. They are intended to help serialize FormatTypes for
+  // IPC messages.
+  static std::string FormatTypeToString(const FormatType& type);
+  static FormatType StringToFormatType(const std::string& format_string);

[tony, 2011/12/06 18:58:29]

Why not just call these methods SerializeFormatType and DeserializeFormatType. 
You could even put these methods on FormatType.

[dcheng, 2011/12/06 22:57:02]

Done.

+
+  // Get format identifiers for various types.
+  static const FormatType& GetUrlFormatType();
+  static const FormatType& GetUrlWFormatType();
+  static const FormatType& GetMozUrlFormatType();
+  static const FormatType& GetPlainTextFormatType();
+  static const FormatType& GetPlainTextWFormatType();
+  static const FormatType& GetFilenameFormatType();
+  static const FormatType& GetFilenameWFormatType();
+  static const FormatType& GetWebKitSmartPasteFormatType();
   // Win: MS HTML Format, Other: Generic HTML format
-  static FormatType GetHtmlFormatType();
-  static FormatType GetBitmapFormatType();
-  static FormatType GetWebCustomDataFormatType();
+  static const FormatType& GetHtmlFormatType();
+  static const FormatType& GetBitmapFormatType();
+  static const FormatType& GetWebCustomDataFormatType();
 
   // Embeds a pointer to a SharedMemory object pointed to by |bitmap_handle|
   // belonging to |process| into a shared bitmap [CBF_SMBITMAP] slot in
@@ -198,10 +244,10 @@ class UI_EXPORT Clipboard {
                                      base::ProcessHandle process);
 #if defined(OS_WIN)
   // Firefox text/html
-  static FormatType GetTextHtmlFormatType();
-  static FormatType GetCFHDropFormatType();
-  static FormatType GetFileDescriptorFormatType();
-  static FormatType GetFileContentFormatZeroType();
+  static const FormatType& GetTextHtmlFormatType();
+  static const FormatType& GetCFHDropFormatType();
+  static const FormatType& GetFileDescriptorFormatType();
+  static const FormatType& GetFileContentFormatZeroType();
 #endif
 
  private:
@@ -226,9 +272,9 @@ class UI_EXPORT Clipboard {
 
   void WriteBitmap(const char* pixel_data, const char* size_data);
 
-  // |format_name| is an ASCII string and should be NULL-terminated.
-  void WriteData(const char* format_name, size_t format_len,
-                 const char* data_data, size_t data_len);
+  void WriteData(const FormatType& format,
+                 const char* data_data,
+                 size_t data_len);
 #if defined(OS_WIN)
   void WriteBitmapFromHandle(HBITMAP source_hbitmap,
                              const gfx::Size& size);
@@ -262,7 +308,7 @@ class UI_EXPORT Clipboard {
   // contents of clipboard_data_.
 
  public:
-  typedef std::map<FormatType, std::pair<char*, size_t> > TargetMap;
+  typedef std::map<std::string, std::pair<char*, size_t> > TargetMap;
 
  private:
   // Write changes to gtk clipboard.