Add the plumbing that will carry a clipboard item from a chromoting client to a host.

remoting/proto/event.proto

Index: remoting/proto/event.proto
diff --git a/remoting/proto/event.proto b/remoting/proto/event.proto
index dcc2aaebea7d2dfeeb67fcca54608612886f631c..1dabf70ea9a2877302ac74bc375420e6384b5be4 100644
--- a/remoting/proto/event.proto
+++ b/remoting/proto/event.proto
@@ -48,3 +48,13 @@ message MouseEvent {
   optional MouseButton button = 5;
   optional bool button_down = 6;
 }
+
+// Defines an event that sends clipboard data between peers.
+message ClipboardEvent {

[Wez, 2012/03/14 20:40:56]

I thought that we had agreed on TextClipboardEvent containing just a UTF-8
encoded string for now, with the intent being to move to a
multi-MIME-type-capable multi-channel protocol in future?

[simonmorris, 2012/03/14 21:20:21]

We may be able to use this message as it stands in such a protocol. Keeping the
MIME type in the message costs very little, and keeps that option open.

+
+  // The MIME type of the data being sent.
+  required string mime_type = 1;

[Sergey Ulanov, 2012/03/14 20:27:07]

It's usually better to mark all fields in protobuf messages as optional.
Otherwise it would be more difficult to make them optional in the future if we
need to.

[simonmorris, 2012/03/14 21:20:21]

Done.

+
+  // The data being sent.
+  required bytes data = 2;
+}