Componentize renderer side of DNS prefetching.

components/predictor/common/predictor_messages.h

Index: components/predictor/common/predictor_messages.h
diff --git a/components/predictor/common/predictor_messages.h b/components/predictor/common/predictor_messages.h
new file mode 100644
index 0000000000000000000000000000000000000000..7928b3b901d1523e8cd17720f632475c1df6370c
--- /dev/null
+++ b/components/predictor/common/predictor_messages.h
@@ -0,0 +1,21 @@
+// Copyright (c) 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.
+
+// Multiply-included file, no traditional include guard.
+#include <string>
+#include <vector>
+
+#include "ipc/ipc_message_macros.h"
+#include "ipc/ipc_message_utils.h"
+
+#define IPC_MESSAGE_START DnsPredictorMsgStart
+
+//-----------------------------------------------------------------------------
+// Host messages
+// These are messages sent from the browser to the renderer process.
+
+// Request for a DNS prefetch of the names in the array.
+// NameList is typedef'ed std::vector<std::string>
+IPC_MESSAGE_CONTROL1(DnsPredictorMsg_RequestPrefetch,
+                     std::vector<std::string> /* hostnames */)

[palmer, 2014/10/13 23:56:21]

Does the receiver of this message set any hard limit on the size of the vector
and the sizes of the strings?

[gunsch, 2014/10/14 15:54:38]

As far as I can tell, in Chrome's current implementation, the limit is only
enforced on the renderer (sender) side. (which makes me notice the IPC comment
was backwards, the IPC message is sent _to_ the browser process).

Some light codesearching seems to imply that's the general case, can you point
me to some similar receiver-side limits on IPC vectors?