WIP: X clipboard stuff

chrome/browser/gtk/xclipboard.h

+struct XClipboardImpl;  // to hide Xlib headers
+
+class XClipboard {
+ public:
+  // display: the X server display to use. This is a void* to avoid polluting the namespace.
+  // delegate: an object which acts on events from the X server. All callbacks
+  //   are made in the context of the thread which is running this object and
+  //   will block processing if they block.
+  XClipboard(void* display, Delegate* delegate);
+
+  ~XClipboard();
+
+  // X understands an arbitary number of clipboard types. However, three are
+  // defined in the specs and two of those are actually used. the PRIMARY
+  // clipboard is used for the current selection. The CLIPBOARD clipboard is
+  // used when the user hits Ctrl-C or "Copy" from a menu etc.
+  enum Type {
+    CLIPBOARD_PRIMARY,
+    CLIPBOARD_SECONDARY,
+    CLIPBOARD_CLIPBOARD,
+  };
+
+  // Content types are passed around as strings.
+  typedef const std::string& ContentType;
+
+  class Delegate {
+    // This is called when we loose ownership of the given clipboard.
+    void ClipboardLost(Type);
+
+    // This is called when another client has requested the current clipboard
+    // contents. You can call ReplyWith* from within this callback.
+    void ClipboardContentsRequested(Type, uint64_t tag, ContentType);
+
+    // This is called when a clipboard request has completed (successfully or
+    // otherwise)
+    //   tag: the value given to |RequestClipboard|
+    //   success: true if |type| and |data| is valid
+    //   type: the type of the data
+    //   data: chunks of data. You must free these chunks.
+    void ClipboardRequestComplete(
+      uint64_t tag, bool success, ContentType type,
+      const std::vector<pair<uint8_t*, size_t> > &data);
+  };
+
+  // Assert that we own the given clipboard. If this returns true, then we own
+  // the given clipboard and ClipboardLost will be called when someone else
+  // takes it from us.
+  bool AssertOwnership(Type);
+
+  // Reply negatively to a request.
+  void ReplyWithFailure(uint64_t tag);
+
+  // Reply positivly to a clipboard request.
+  //   tag: the value given in the |ClipboardContentsRequested| callback
+  //   data: bytes to reply with.
+  //   length: the length of |data|, in bytes
+  // This function may block arbitarity if the other client misbehaves. Also,
+  // this function may only enqueue the reply if ordering constrains proclude
+  // its immediate transmission.
+  void ReplyWithContents(uint64_t tag, const uint8_t* data, size_t length);
+
+  // Request the current contents of the given clipboard in the given format.
+  void RequestClipboard(uint64_t tag, Type, ContentType);
+
+ private:
+  Delegate* const delegate_;
+  XClipboardImpl* const pimpl_;
+};