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

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

Index: chrome/browser/extensions/api/debugger/debugger_api.h
diff --git a/chrome/browser/extensions/api/debugger/debugger_api.h b/chrome/browser/extensions/api/debugger/debugger_api.h
index 086b4c4927c897113a6574da51411926fa546a14..d56bb15a5ad8b2c99d66262e39a868913884f6d3 100644
--- a/chrome/browser/extensions/api/debugger/debugger_api.h
+++ b/chrome/browser/extensions/api/debugger/debugger_api.h
@@ -86,4 +86,18 @@ class DebuggerSendCommandFunction : public DebuggerFunction {
   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_