Introduce DevToolsExternalAgentProxy interface

content/browser/devtools/render_view_devtools_agent_host.cc

 // 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.
 
 #include "content/browser/devtools/render_view_devtools_agent_host.h"
 
 #include "base/base64.h"
 #include "base/basictypes.h"
 #include "base/lazy_instance.h"
 #include "content/browser/child_process_security_policy_impl.h"
@@ skipping 177 matching lines @@
   if (!command) {
     OnDispatchOnInspectorFrontend(error_message);
     return;
   }
 
   scoped_ptr<DevToolsProtocol::Response> overridden_response(
       overrides_handler_->HandleCommand(command.get()));
   if (overridden_response)
     OnDispatchOnInspectorFrontend(overridden_response->Serialize());
   else
-    DevToolsAgentHostImpl::DispatchOnInspectorBackend(message);
+    IPCDevToolsAgentHost::DispatchOnInspectorBackend(message);
 }
 
 void RenderViewDevToolsAgentHost::SendMessageToAgent(IPC::Message* msg) {
   if (!render_view_host_)
     return;
   msg->set_routing_id(render_view_host_->GetRoutingID());
   render_view_host_->Send(msg);
 }
 
 void RenderViewDevToolsAgentHost::NotifyClientAttaching() {
@@ skipping 167 matching lines @@
                             snapshot_bounds))
     return false;
 
   return base::Base64Encode(base::StringPiece(
                                 reinterpret_cast<char*>(&*png.begin()),
                                 png.size()),
                             base_64_data);
 }
 
 }  // namespace content