Require an explicit ServiceName annotation for interfaces in C++.

mojo/services/clipboard/interfaces/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.
 
 [DartPackage="mojo_services"]
 module mojo;
 
+[ServiceName="mojo::Clipboard"]
 interface Clipboard {
   enum Type {
     COPY_PASTE = 0,
     SELECTION = 1,
     DRAG = 2
   };
 
   // Mime type constants
   const string MIME_TYPE_TEXT = "text/plain";
   const string MIME_TYPE_HTML = "text/html";
@@ skipping 17 matching lines @@
   // GetAvailableFormatMimeTypes(). We don't want to provide one API to return
   // the entire clipboard state because the combined size of the clipboard can
   // be megabytes, especially when image data is involved.
   ReadMimeType(Type clipboard_type, string mime_type) => (array<uint8>? data);
 
   // Writes a set of mime types to the clipboard. This will increment the
   // sequence number. In the case of an empty or null map, this will just
   // clear the clipboard.
   WriteClipboardData(Type clipboard_type, map<string, array<uint8>>? data);
 };