[Extensions] Clean up the handling of ExtensionHostMsg_Request

extensions/browser/test_extensions_browser_client.cc

 // Copyright 2014 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 "extensions/browser/test_extensions_browser_client.h"
 
 #include "content/public/browser/browser_context.h"
 #include "extensions/browser/app_sorting.h"
 #include "extensions/browser/extension_host_delegate.h"
 #include "extensions/browser/test_runtime_api_delegate.h"
@@ skipping 180 matching lines @@
 
 bool TestExtensionsBrowserClient::IsBackgroundUpdateAllowed() {
   return true;
 }
 
 bool TestExtensionsBrowserClient::IsMinBrowserVersionSupported(
     const std::string& min_version) {
   return true;
 }
 
+ExtensionWebContentsObserver*
+TestExtensionsBrowserClient::GetExtensionWebContentsObserver(
+    content::WebContents* web_contents) {
+  return nullptr;
+}
+
 }  // namespace extensions