Have the Debugger extension api check that it has access to the tab

chrome/test/data/extensions/api_test/debugger/background.js

 // Copyright (c) 2011 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.
 
 var pass = chrome.test.callbackPass;
 var fail = chrome.test.callbackFail;
 
 var tabId;
 var debuggee;
 var protocolVersion = "1.1";
@@ skipping 90 matching lines @@
         chrome.debugger.onDetach.addListener(onDetach);
         chrome.tabs.remove(tab.id);
       });
     });
   },
 
   function attachToWebUI() {
     chrome.tabs.create({url:"chrome://version"}, function(tab) {
       var debuggee = {tabId: tab.id};
       chrome.debugger.attach(debuggee, protocolVersion,
-          fail("Can not attach to the page with the \"chrome://\" scheme."));
+          fail("Cannot access a chrome:// URL"));
       chrome.tabs.remove(tab.id);
     });
   },
 
   function attachToMissing() {
     var missingDebuggee = {tabId: -1};
     chrome.debugger.attach(missingDebuggee, protocolVersion,
         fail("No tab with given id " + missingDebuggee.tabId + "."));
   },
 
@@ skipping 78 matching lines @@
       function onAttach() {
         chrome.debugger.sendCommand(debuggee, "Page.enable");
         chrome.debugger.sendCommand(
             debuggee, "Page.navigate", {url:"about:blank"}, onNavigateDone);
       }
 
       chrome.debugger.attach(debuggee, protocolVersion, onAttach);
     });
   }
 ]);