Add chrome.debugger.getTargets method to discover available debug targets.

chrome/browser/extensions/api/debugger/debugger_api.h

 // 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.
 
 // Defines the Chrome Extensions Debugger API functions for attaching debugger
 // to the page.
 
 #ifndef CHROME_BROWSER_EXTENSIONS_API_DEBUGGER_DEBUGGER_API_H_
 #define CHROME_BROWSER_EXTENSIONS_API_DEBUGGER_DEBUGGER_API_H_
 
@@ skipping 68 matching lines @@
   DebuggerSendCommandFunction();
   void SendResponseBody(base::DictionaryValue* result);
 
  protected:
   virtual ~DebuggerSendCommandFunction();
 
   // ExtensionFunction:
   virtual bool RunImpl() OVERRIDE;
 };
 
+// Implements the debugger.getTargets() extension function.
+class DebuggerGetTargetsFunction : public DebuggerFunction {
+ public:
+  DECLARE_EXTENSION_FUNCTION("debugger.getTargets", DEBUGGER_ATTACH)
+
+  DebuggerGetTargetsFunction();
+
+ protected:
+  virtual ~DebuggerGetTargetsFunction();
+
+  // ExtensionFunction:
+  virtual bool RunImpl() OVERRIDE;
+};
+
 #endif  // CHROME_BROWSER_EXTENSIONS_API_DEBUGGER_DEBUGGER_API_H_