Componentize component_updater: Replace content::BrowserThread usage with task runners

chrome/browser/component_updater/default_component_installer.h

 // 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.
 
 #ifndef CHROME_BROWSER_COMPONENT_UPDATER_DEFAULT_COMPONENT_INSTALLER_H_
 #define CHROME_BROWSER_COMPONENT_UPDATER_DEFAULT_COMPONENT_INSTALLER_H_
 
 #include <string>
 #include <vector>
 
 #include "base/compiler_specific.h"
+#include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/threading/thread_checker.h"
 #include "base/version.h"
 #include "chrome/browser/component_updater/component_updater_service.h"
 
 namespace base {
 class DictionaryValue;
 class FilePath;
+class SequencedTaskRunner;
+class SingleThreadTaskRunner;
 }  // namespace base
 
 namespace component_updater {
 
 // Components should use a DefaultComponentInstaller by defining a class that
 // implements the members of ComponentInstallerTraits, and then registering a
 // DefaultComponentInstaller that has been constructed with an instance of that
 // class.
 class ComponentInstallerTraits {
  public:
@@ skipping 40 matching lines @@
 
   // Returns the human-readable name of the component.
   virtual std::string GetName() const = 0;
 };
 
 // A DefaultComponentInstaller is intended to be final, and not derived from.
 // Customization must be provided by passing a ComponentInstallerTraits object
 // to the constructor.
 class DefaultComponentInstaller : public ComponentInstaller {
  public:
-  explicit DefaultComponentInstaller(
+  DefaultComponentInstaller(
       scoped_ptr<ComponentInstallerTraits> installer_traits);
 
   // Registers the component for update checks and installs.
   void Register(ComponentUpdateService* cus);
 
   // Overridden from ComponentInstaller:
   virtual void OnUpdateError(int error) OVERRIDE;
   virtual bool Install(const base::DictionaryValue& manifest,
                        const base::FilePath& unpack_path) OVERRIDE;
   virtual bool GetInstalledFile(const std::string& file,
                                 base::FilePath* installed_file) OVERRIDE;
 
   virtual ~DefaultComponentInstaller();
 
  private:
   base::FilePath GetInstallDirectory();
   bool InstallHelper(const base::DictionaryValue& manifest,
                      const base::FilePath& unpack_path,
                      const base::FilePath& install_path);
   void StartRegistration(ComponentUpdateService* cus);
   void FinishRegistration(ComponentUpdateService* cus);
 
   base::Version current_version_;
   std::string current_fingerprint_;
   scoped_ptr<base::DictionaryValue> current_manifest_;
   scoped_ptr<ComponentInstallerTraits> installer_traits_;
+  scoped_refptr<base::SequencedTaskRunner> task_runner_;
+
+  // Used to post responses back to the main thread. Initialized on the main
+  // loop but accessed from the task runner.
+  scoped_refptr<base::SingleThreadTaskRunner> main_task_runner_;
+
+  base::ThreadChecker thread_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(DefaultComponentInstaller);
 };
 
 }  // namespace component_updater
 
 #endif  // CHROME_BROWSER_COMPONENT_UPDATER_DEFAULT_COMPONENT_INSTALLER_H_