Empty startup task queue when tasks run synchronously

content/browser/startup_task_runner.cc

 // Copyright 2013 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.
 
 #include "content/browser/startup_task_runner.h"
 
 #include "base/bind.h"
 #include "base/location.h"
 #include "base/message_loop/message_loop.h"
 
 namespace content {
 
 StartupTaskRunner::StartupTaskRunner(
     base::Callback<void(int)> const startup_complete_callback,
     scoped_refptr<base::SingleThreadTaskRunner> proxy)
     : startup_complete_callback_(startup_complete_callback), proxy_(proxy) {}
 
 StartupTaskRunner::~StartupTaskRunner() {}
 
 void StartupTaskRunner::AddTask(StartupTask& callback) {
   task_list_.push_back(callback);
 }
 
 void StartupTaskRunner::StartRunningTasksAsync() {
   DCHECK(proxy_);
   int result = 0;
   if (task_list_.empty()) {
     if (!startup_complete_callback_.is_null()) {
       startup_complete_callback_.Run(result);
+      // Clear the callback to prevent it being called a second time
+      startup_complete_callback_.Reset();
     }
   } else {
     const base::Closure next_task =
         base::Bind(&StartupTaskRunner::WrappedTask, base::Unretained(this));
     proxy_->PostNonNestableTask(FROM_HERE, next_task);
   }
 }
 
 void StartupTaskRunner::RunAllTasksNow() {
   int result = 0;
   for (std::list<StartupTask>::iterator it = task_list_.begin();
        it != task_list_.end();
        it++) {
     result = it->Run();
     if (result > 0) break;
   }
+  task_list_.clear();
   if (!startup_complete_callback_.is_null()) {
     startup_complete_callback_.Run(result);
+    // Clear the callback to prevent it being called a second time
+    startup_complete_callback_.Reset();
   }
 }
 
 void StartupTaskRunner::WrappedTask() {
   if (task_list_.empty()) {
     // This will happen if the remaining tasks have been run synchronously since
     // the WrappedTask was created. Any callback will already have been called,
     // so there is nothing to do
     return;
   }
   int result = task_list_.front().Run();
   task_list_.pop_front();
-  if (result > 0 || task_list_.empty()) {
+  if (result > 0) {
+    // Stop now and throw away the remaining tasks
+    task_list_.clear();
+  }
+  if (task_list_.empty()) {
     if (!startup_complete_callback_.is_null()) {
       startup_complete_callback_.Run(result);
+      // Clear the callback to prevent it being called a second time
+      startup_complete_callback_.Reset();
     }
   } else {
     const base::Closure next_task =
         base::Bind(&StartupTaskRunner::WrappedTask, base::Unretained(this));
     proxy_->PostNonNestableTask(FROM_HERE, next_task);
   }
 }
 
 }  // namespace content