[Extensions] Isolate ExtensionFunction results_ and error_

chrome/browser/extensions/chrome_extension_function.h

Index: chrome/browser/extensions/chrome_extension_function.h
diff --git a/chrome/browser/extensions/chrome_extension_function.h b/chrome/browser/extensions/chrome_extension_function.h
index a556085562dbf13e8e890d95ba37327bc9d5243f..59d5e1e0ad19324de4bbbe795683da57d1149514 100644
--- a/chrome/browser/extensions/chrome_extension_function.h
+++ b/chrome/browser/extensions/chrome_extension_function.h
@@ -54,16 +54,31 @@ class ChromeUIThreadExtensionFunction : public UIThreadExtensionFunction {
   // Same as above but uses WindowControllerList instead of BrowserList.
   extensions::WindowController* GetExtensionWindowController();
 
-  // Gets the "current" web contents if any. If there is no associated web
-  // contents then defaults to the foremost one.
+  // ExtensionFunction:
   content::WebContents* GetAssociatedWebContents() override;
+  void SetError(const std::string& error) override;
+  const std::string& GetError() const override;
+
+ protected:
+  ~ChromeUIThreadExtensionFunction() override;
 
   // Responds with success/failure. |results_| or |error_| should be set
   // accordingly.
   void SendResponse(bool success);
 
- protected:
-  ~ChromeUIThreadExtensionFunction() override;
+  // Sets a single Value as the results of the function.
+  void SetResult(std::unique_ptr<base::Value> result);
+
+  // Sets multiple Values as the results of the function.
+  void SetResultList(std::unique_ptr<base::ListValue> results);
+
+  // Exposed versions of ExtensionFunction::results_ and
+  // ExtensionFunction::error_ that are curried into the response.
+  // These need to keep the same name to avoid breaking existing
+  // implementations, but this should be temporary with crbug.com/648275
+  // and crbug.com/634140.
+  std::unique_ptr<base::ListValue> results_;
+  std::string error_;
 
  private:
   ChromeExtensionFunctionDetails chrome_details_;