Add option --dump-render-tree to content_shell to dump the render tree as text.

content/shell/shell_messages.cc

Index: content/shell/shell_messages.cc
diff --git a/content/shell/shell_messages.cc b/content/shell/shell_messages.cc
new file mode 100644
index 0000000000000000000000000000000000000000..422299f65cc5a27f9aaf980a52cebc21107cbf4f
--- /dev/null
+++ b/content/shell/shell_messages.cc
@@ -0,0 +1,33 @@
+// 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.
+
+// Get basic type definitions.
+#define IPC_MESSAGE_IMPL
+#include "content/shell/shell_messages.h"
+
+// Generate constructors.
+#include "ipc/struct_constructor_macros.h"
+#include "content/shell/shell_messages.h"
+
+// Generate destructors.
+#include "ipc/struct_destructor_macros.h"
+#include "content/shell/shell_messages.h"
+
+// Generate param traits write methods.
+#include "ipc/param_traits_write_macros.h"
+namespace IPC {
+#include "content/shell/shell_messages.h"
+}  // namespace IPC
+
+// Generate param traits read methods.
+#include "ipc/param_traits_read_macros.h"
+namespace IPC {
+#include "content/shell/shell_messages.h"
+}  // namespace IPC
+
+// Generate param traits log methods.
+#include "ipc/param_traits_log_macros.h"
+namespace IPC {
+#include "content/shell/shell_messages.h"
+}  // namespace IPC