mojo: Create a basic clipboard.

mojo/services/public/interfaces/clipboard/clipboard.mojom

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+module mojo {
+
+interface Clipboard {
+  enum Type {
+    COPY_PASTE,
+    SELECTION,
+    DRAG
+  };
+
+  // Mime type constants
+  const string MIME_TYPE_TEXT = "text/plain";
+  const string MIME_TYPE_HTML = "text/html";
+
+  // Returns a sequence number which uniquely identifies clipboard state.
+  GetSequenceNumber(Type clipboard_type) => (uint64 sequence);

[sky, 2014/09/11 19:52:39]

Does sequence really need to be uint64?
I'm not sure I get the value of the sequence number. It isn't checked any where.
What is it for?

[dcheng, 2014/09/11 20:06:21]

This is used inside Blink to prevent a malicious script from repeatedly polling
event.clipboardData after the contents change.

[Elliot Glaysher, 2014/09/11 21:42:28]

I've added to this comment that sequence numbers are part of the clipboard
interface provided by all major operating systems, that they're monotonically
increasing, and that they increase on write.

+
+  // Returns the available mime types. (Note: the chrome interface has a
+  // |contains_filenames| parameter here, but it appears to always be set
+  // to false.)
+  GetAvailableFormatMimeTypes(Type clipboard_types) => (string[] types);
+
+  ReadPlainText(Type clipboard_type) => (string text);
+  ReadHTML(Type clipboard_type) =>
+      (string html, string url, uint32 fragment_start, uint32 fragment_end);
+  ReadMIMEType(Type clipboard_type, string mime_type) => (string data);
+  // TODO: We probably want an image type.
+
+  // Clipboard Writing
+  //
+  // Clipboard writing is a two phase operation, where a client queues all data
+  // types that they want written to the clipboard, and then writes all queued
+  // data in one pass. We do this to prevent racing with other applications on
+  // the system.
+
+  // Queue writing individual datatypes to specific clipboards.
+  QueueWritePlainText(Type clipboard_type, string text);
+  QueueWriteHTML(Type clipboard_type, string html_text, string url);
+  QueueWriteMIMEType(Type clipboard_type, string mime_type, string data);
+  // TODO: We probably want an image type.
+
+  // Writes all queued data types in one pass.
+  WriteQueuedData(Type clipboard_type);
+};
+
+}  // module mojo