Install and launch kiosk app from cached crx file at start up.

chrome/browser/chromeos/extensions/external_cache.h

 // Copyright (c) 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_CHROMEOS_EXTENSIONS_EXTERNAL_CACHE_H_
 #define CHROME_BROWSER_CHROMEOS_EXTENSIONS_EXTERNAL_CACHE_H_
 
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 85 matching lines @@
       const GURL& download_url,
       const std::string& version,
       const PingResult& ping_result,
       const std::set<int>& request_ids) OVERRIDE;
 
   virtual bool IsExtensionPending(const std::string& id) OVERRIDE;
 
   virtual bool GetExtensionExistingVersion(const std::string& id,
                                            std::string* version) OVERRIDE;
 
+  // Returns true if the extension with |id| is pending for update check.
+  bool IsExtensionPendingForUpdateCheck(const std::string& id);

[xiyuan, 2014/05/29 19:49:01]

Move this under IsExtensionPending so that it has the same location as in cc
file.

[jennyz, 2014/07/07 21:11:12]

Since this one is not virtual, so I won't put it under IsExtensionPending,
unless we add it to the ExtensionDownloaderDelegate. Moved its location is cc to
keep the order consistent with .h.

+
   // Shut down the cache. The |callback| will be invoked when the cache has shut
   // down completely and there are no more pending file I/O operations.
   void Shutdown(const base::Closure& callback);
 
   // Replace the list of extensions to cache with |prefs| and perform update
   // checks for these.
   void UpdateExtensionsList(scoped_ptr<base::DictionaryValue> prefs);
 
   // If a user of one of the ExternalCache's extensions detects that
   // the extension is damaged then this method can be used to remove it from
   // the cache and retry to download it after a restart.
   void OnDamagedFileDetected(const base::FilePath& path);
 
   // Removes extensions listed in |ids| from external cache, corresponding crx
   // files will be removed from disk too.
   void RemoveExtensions(const std::vector<std::string>& ids);
 
   // If extension with |id| exists in the cache, returns |true|, |file_path| and
   // |version| for the extension. Extension will be marked as used with current
   // timestamp.
   bool GetExtension(const std::string& id,
                     base::FilePath* file_path,
                     std::string* version);
 
  private:
+  enum ExtensionStatus {
+    DOWNLOAD_PENDING,
+    DOWNLOAD_SUCCEEDED,
+    DOWNLOAD_FAILED,
+  };
+
   // Notifies the that the cache has been updated, providing
   // extensions loader with an updated list of extensions.
   void UpdateExtensionLoader();
 
   // Checks the cache contents and initiate download if needed.
   void CheckCache();
 
   // Invoked on the UI thread when a new entry has been installed in the cache.
   void OnPutExtension(const std::string& id,
                       const base::FilePath& file_path,
@@ skipping 16 matching lines @@
   // Set to true if cache should wait for initialization flag file.
   bool wait_for_cache_initialization_;
 
   // This is the list of extensions currently configured.
   scoped_ptr<base::DictionaryValue> extensions_;
 
   // This contains extensions that are both currently configured
   // and that have a valid crx in the cache.
   scoped_ptr<base::DictionaryValue> cached_extensions_;
 
+  // <extension_id : status>: used for tracking extension download status.
+  std::map<std::string, ExtensionStatus> extensions_status_;
+
   // Used to download the extensions and to check for updates.
   scoped_ptr<extensions::ExtensionDownloader> downloader_;
 
   // Observes failures to install CRX files.
   content::NotificationRegistrar notification_registrar_;
 
   // Weak factory for callbacks.
   base::WeakPtrFactory<ExternalCache> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ExternalCache);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_EXTENSIONS_EXTERNAL_CACHE_H_