[DevTools] Make sendMessageToBackend one of embedder messages.

content/shell/browser/shell_devtools_frontend.h

 // Copyright 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_SHELL_BROWSER_SHELL_DEVTOOLS_FRONTEND_H_
 #define CONTENT_SHELL_BROWSER_SHELL_DEVTOOLS_FRONTEND_H_
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/memory/ref_counted.h"
@@ skipping 32 matching lines @@
   virtual ~ShellDevToolsFrontend();
 
   // WebContentsObserver overrides
   virtual void RenderViewCreated(RenderViewHost* render_view_host) OVERRIDE;
   virtual void DocumentOnLoadCompletedInMainFrame() OVERRIDE;
   virtual void WebContentsDestroyed() OVERRIDE;
   virtual void RenderProcessGone(base::TerminationStatus status) OVERRIDE;
 
   // content::DevToolsFrontendHost::Delegate implementation.
   virtual void HandleMessageFromDevToolsFrontend(
-      const std::string& message) OVERRIDE {}
+      const std::string& message) OVERRIDE;
   virtual void HandleMessageFromDevToolsFrontendToBackend(
       const std::string& message) OVERRIDE;
 
   // content::DevToolsClientHost implementation.
   virtual void DispatchOnInspectorFrontend(const std::string& message) OVERRIDE;
   virtual void InspectedContentsClosing() OVERRIDE;
   virtual void ReplacedWithAnotherClient() OVERRIDE {}
 
   Shell* frontend_shell_;
   scoped_refptr<DevToolsAgentHost> agent_host_;
   scoped_ptr<DevToolsFrontendHost> frontend_host_;
 
   DISALLOW_COPY_AND_ASSIGN(ShellDevToolsFrontend);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_SHELL_BROWSER_SHELL_DEVTOOLS_FRONTEND_H_