Allow chrome.debugger API to attach to extension background pages.

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 debuggeeExtension;
 var protocolVersion = "1.0";
 
 chrome.test.runTests([
 
   function attachMalformedVersion() {
     chrome.tabs.getSelected(null, function(tab) {
       chrome.debugger.attach({tabId: tab.id}, "malformed-version",
           fail("Requested protocol version is not supported: malformed-version."));
     });
   },
@@ skipping 13 matching lines @@
   },
 
   function attach() {
     chrome.tabs.getSelected(null, function(tab) {
       tabId = tab.id;
       debuggee = {tabId: tab.id};
       chrome.debugger.attach(debuggee, protocolVersion, pass());
     });
   },
 
+  function attachToMissingTab() {
+     var missingDebuggee = {tabId: -1};
+     chrome.debugger.attach(missingDebuggee, protocolVersion,
+        fail("No tab with given id " + missingDebuggee.tabId + "."));
+  },
+
   function attachAgain() {
     chrome.debugger.attach(debuggee, protocolVersion,
         fail("Another debugger is already attached to the tab with id: " +
                  tabId + "."));
   },
 
   function sendCommand() {
     function onResponse() {
       if (chrome.runtime.lastError &&
           chrome.runtime.lastError.message.indexOf("invalidMethod") != -1)
@@ skipping 38 matching lines @@
     });
   },
 
   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."));
       chrome.tabs.remove(tab.id);
     });
-  }
+  },
 
+  function attachToExtension() {
+    var extensionId = chrome.extension.getURL('').split('/')[2];
+    debuggeeExtension = {extensionId: extensionId};
+    chrome.debugger.attach(debuggeeExtension, protocolVersion, pass());
+  },
+
+  function attachToMissingExtension() {
+    var missingDebuggee = {extensionId: "foo"};
+    chrome.debugger.attach(missingDebuggee, protocolVersion,
+        fail("No extension with given id " +
+            missingDebuggee.extensionId + "."));
+  },
+
+  function attachToInvalidTarget() {
+    var emptyDebuggee = {};
+    chrome.debugger.attach(emptyDebuggee, protocolVersion,
+        fail("Either tab id or extension id must be specified."));
+  },
+
+  function attachAgainToExtension() {
+    chrome.debugger.attach(debuggeeExtension, protocolVersion,
+        fail("Another debugger is already attached to the extension with id: " +
+            debuggeeExtension.extensionId + "."));
+  },
+
+  function detachFromExtension() {
+    chrome.debugger.detach(debuggeeExtension, pass());
+  },
+
+  function detachAgainFromExtension() {
+    chrome.debugger.detach(debuggeeExtension,
+        fail("Debugger is not attached to the extension with id: " +
+            debuggeeExtension.extensionId + "."));
+  },
 ]);