Support frame tree propagation between renderers in the same browsing instance.

content/common/renderer_constants.h

Index: content/common/renderer_constants.h
diff --git a/content/common/renderer_constants.h b/content/common/renderer_constants.h
new file mode 100644
index 0000000000000000000000000000000000000000..c83e8c112108ea680fc756d7b3d8e9b3ffb5025f
--- /dev/null
+++ b/content/common/renderer_constants.h
@@ -0,0 +1,18 @@
+// Copyright (c) 2012 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.
+
+#ifndef CONTENT_COMMON_RENDERER_CONSTANTS_H_
+#define CONTENT_COMMON_RENDERER_CONSTANTS_H_

[Charlie Reis, 2012/08/22 22:08:34]

I don't have a better name yet, but it feels weird to me to have a
renderer_constants.h in common.  I agree that they don't belong in
public/common/content_constants.h, but I wonder if some kind of
content_constants_impl.h or frame_tree_constants.h would be better.

[nasko, 2012/08/23 21:55:53]

Done.

+
+namespace content {
+
+// Keys used for serializing the frame tree of a renderer process, used for
+// ViewMsg_UpdateFrameTree and ViewHostMsg_FrameTreeUpdated.
+extern const char kFrameTreeNodeNameKey[];
+extern const char kFrameTreeNodeIdKey[];
+extern const char kFrameTreeNodeSubtreeKey[];
+
+} // namespace content
+
+#endif  // CONTENT_COMMON_RENDERER_CONSTANTS_H_