[Extensions] Apply WARN_UNUSED_RESULT and final keyword to ExtensionFunctions.

extensions/browser/extension_function.h

Index: extensions/browser/extension_function.h
diff --git a/extensions/browser/extension_function.h b/extensions/browser/extension_function.h
index 2e367d33be8597b8c88442b1ea5aedbc966f1806..de1358663a8c8403060db29e6e706d89f26298bd 100644
--- a/extensions/browser/extension_function.h
+++ b/extensions/browser/extension_function.h
@@ -322,14 +322,15 @@ class ExtensionFunction
   // ResponseActions.
   //
   // Respond to the extension immediately with |result|.
-  ResponseAction RespondNow(ResponseValue result);
+  ResponseAction RespondNow(ResponseValue result) WARN_UNUSED_RESULT;
   // Don't respond now, but promise to call Respond(...) later.
-  ResponseAction RespondLater();
+  ResponseAction RespondLater() WARN_UNUSED_RESULT;
 
   // This is the return value of the EXTENSION_FUNCTION_VALIDATE macro, which
   // needs to work from Run(), RunAsync(), and RunSync(). The former of those
   // has a different return type (ResponseAction) than the latter two (bool).
-  static ResponseAction ValidationFailure(ExtensionFunction* function);
+  static ResponseAction ValidationFailure(ExtensionFunction* function)
+      WARN_UNUSED_RESULT;
 
   // If RespondLater() was used, functions must at some point call Respond()
   // with |result| as their result.
@@ -588,7 +589,7 @@ class AsyncExtensionFunction : public UIThreadExtensionFunction {
   static bool ValidationFailure(AsyncExtensionFunction* function);
 
  private:
-  ResponseAction Run() override;
+  ResponseAction Run() final;
 };
 
 // A SyncExtensionFunction is an ExtensionFunction that runs synchronously
@@ -615,7 +616,7 @@ class SyncExtensionFunction : public UIThreadExtensionFunction {
   static bool ValidationFailure(SyncExtensionFunction* function);
 
  private:
-  ResponseAction Run() override;
+  ResponseAction Run() final;
 };
 
 class SyncIOThreadExtensionFunction : public IOThreadExtensionFunction {
@@ -636,7 +637,7 @@ class SyncIOThreadExtensionFunction : public IOThreadExtensionFunction {
   static bool ValidationFailure(SyncIOThreadExtensionFunction* function);
 
  private:
-  ResponseAction Run() override;
+  ResponseAction Run() final;
 };
 
 #endif  // EXTENSIONS_BROWSER_EXTENSION_FUNCTION_H_