Convert FeedbackPrivateGetStringsFunction to OnceClosure

This class has a test method that allows storing a closure to be called
when this ExtensionFunction is invoked. Since ExtensionFunctions should
only call Run() (at most) once, this Closure can be a OnceClosure.

We also clean it up to avoid using a pointer.

Bug: 1152268
Change-Id: Ie7ebc98ad8569ac31f8b6b553426c2bc40c3ea8a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2602888Reviewed-by: Ahmed Fakhry <afakhry@chromium.org>
Commit-Queue: David Bokan <bokan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#840435}

chrome/browser/extensions/api/feedback_private/feedback_browsertest.cc

@@ -65,12 +65,12 @@ class FeedbackTest : public ExtensionBrowserTest {
                        const std::string& extra_diagnostics,
                        bool from_assistant = false,
                        bool include_bluetooth_logs = false) {
-    base::Closure callback = base::Bind(&StopMessageLoopCallback);
+    base::OnceClosure callback = base::BindOnce(&StopMessageLoopCallback);
     extensions::FeedbackPrivateGetStringsFunction::set_test_callback(&callback);
     InvokeFeedbackUI(flow, extra_diagnostics, from_assistant,
                      include_bluetooth_logs);
     content::RunMessageLoop();
-    extensions::FeedbackPrivateGetStringsFunction::set_test_callback(NULL);
+    extensions::FeedbackPrivateGetStringsFunction::set_test_callback(nullptr);
   }
 
   void VerifyFeedbackAppLaunch() {

extensions/browser/api/feedback_private/feedback_private_api.cc

@@ -194,7 +194,7 @@ void FeedbackPrivateAPI::RequestFeedbackForFlow(
 }
 
 // static
-base::Closure* FeedbackPrivateGetStringsFunction::test_callback_ = NULL;
+base::OnceClosure* FeedbackPrivateGetStringsFunction::test_callback_ = nullptr;
 
 ExtensionFunction::ResponseAction FeedbackPrivateGetStringsFunction::Run() {
   auto params = feedback_private::GetStrings::Params::Create(*args_);
@@ -209,7 +209,7 @@ ExtensionFunction::ResponseAction FeedbackPrivateGetStringsFunction::Run() {
           params->flow == FeedbackFlow::FEEDBACK_FLOW_SADTABCRASH);
 
   if (test_callback_ && !test_callback_->is_null())
-    test_callback_->Run();
+    std::move(*test_callback_).Run();
 
   return RespondNow(
       OneArgument(base::Value::FromUniquePtrValue(std::move(dict))));

extensions/browser/api/feedback_private/feedback_private_api.h

@@ -81,7 +81,7 @@ class FeedbackPrivateGetStringsFunction : public ExtensionFunction {
                              FEEDBACKPRIVATE_GETSTRINGS)
 
   // Invoke this callback when this function is called - used for testing.
-  static void set_test_callback(base::Closure* const callback) {
+  static void set_test_callback(base::OnceClosure* callback) {
     test_callback_ = callback;
   }
 
@@ -92,7 +92,7 @@ class FeedbackPrivateGetStringsFunction : public ExtensionFunction {
   ResponseAction Run() override;
 
  private:
-  static base::Closure* test_callback_;
+  static base::OnceClosure* test_callback_;
 };
 
 class FeedbackPrivateGetUserEmailFunction : public ExtensionFunction {