Introduce DevToolsExternalAgentProxy interface

content/public/browser/devtools_external_agent_proxy_delegate.h

Index: content/public/browser/devtools_external_agent_proxy_delegate.h
diff --git a/content/public/browser/devtools_external_agent_proxy_delegate.h b/content/public/browser/devtools_external_agent_proxy_delegate.h
new file mode 100644
index 0000000000000000000000000000000000000000..d68854f23ce49d08f69a82cc1930c204ccb25907
--- /dev/null
+++ b/content/public/browser/devtools_external_agent_proxy_delegate.h
@@ -0,0 +1,32 @@
+// Copyright (c) 2013 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_PUBLIC_BROWSER_DEVTOOLS_EXTERNAL_AGENT_PROXY_DELEGATE_H_
+#define CONTENT_PUBLIC_BROWSER_DEVTOOLS_EXTERNAL_AGENT_PROXY_DELEGATE_H_
+
+#include <string>
+
+#include "content/common/content_export.h"
+
+namespace content {
+
+// Describes the interface for sending messages to an external DevTools agent.
+class DevToolsExternalAgentProxyDelegate {
+ public:
+   // Informs the agent that a client host has attached.
+   virtual void Attach() = 0;
+
+   // Informs the agent that a client host has detached.
+   virtual void Detach() = 0;
+
+   // Sends a message to the agent.
+   virtual void SendMessageToBackend(const std::string& message) = 0;
+
+ protected:
+  virtual ~DevToolsExternalAgentProxyDelegate() {}
+};
+
+}  // namespace content
+
+#endif  // CONTENT_PUBLIC_BROWSER_DEVTOOLS_EXTERNAL_AGENT_PROXY_DELEGATE_H_