Translate: language list smart updater

chrome/browser/translate/translate_language_list.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_TRANSLATE_TRANSLATE_LANGUAGE_LIST_H_
 #define CHROME_BROWSER_TRANSLATE_TRANSLATE_LANGUAGE_LIST_H_
 
 #include <set>
 #include <string>
 #include <vector>
 
 #include "base/callback.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/time.h"
+#include "chrome/browser/web_resource/resource_request_allowed_notifier.h"
 #include "googleurl/src/gurl.h"
 #include "net/url_request/url_fetcher_delegate.h"
 
 namespace net {
 class URLFetcher;
 }
 
 // The TranslateLanguageList class is responsible for maintaining the latest
 // supporting language list.
 // This class is defined to be owned only by TranslateManager.
-class TranslateLanguageList {
+class TranslateLanguageList : public ResourceRequestAllowedNotifier::Observer {
  public:
   TranslateLanguageList();
   virtual ~TranslateLanguageList();
 
   // Returns the last-updated time when the language list is fetched from the
   // Translate server. Returns null time if the list is yet to be fetched.
   base::Time last_updated() { return last_updated_; }
 
   // Fills |languages| with the list of languages that the translate server can
   // translate to and from. |languages| will include alpha languages.
   void GetSupportedLanguages(std::vector<std::string>* languages);
 
   // Returns the language code that can be used with the Translate method for a
   // specified |chrome_locale|.
   std::string GetLanguageCode(const std::string& chrome_locale);
 
   // Returns true if |language| is supported by the translation server. It also
   // returns true against alpha languages.
   bool IsSupportedLanguage(const std::string& language);
 
   // Returns true if |language| is supported by the translation server as a
   // alpha language.
   bool IsAlphaLanguage(const std::string& language);
 
   // Fetches the language list from the translate server. It will not retry
   // more than kMaxRetryLanguageListFetch times. Do nothing if the list is
   // already updated.
   void RequestLanguageList();
 
+  // ResourceRequestAllowedNotifier::Observer implementation:
+  virtual void OnResourceRequestsAllowed() OVERRIDE;
+
   // static const values shared with our browser tests.
   static const char kLanguageListCallbackName[];
   static const char kTargetLanguagesKey[];
 
  private:
   // The LanguageListFetcher class implements a client to fetch a server
   // supported language list. It also maintains the state to represent if the
   // fetch is completed successfully to try again later.
   class LanguageListFetcher : public net::URLFetcherDelegate {
    public:
@@ skipping 32 matching lines @@
     // Internal state.
     enum State state_;
 
     // URLFetcher instance.
     scoped_ptr<net::URLFetcher> fetcher_;
 
     // Callback passed at Request(). It will be invoked when an asynchronous
     // fetch operation is finished.
     Callback callback_;
 
+    // Counts how many times did it try to fetch the language list.
+    int retry_count_;
+
     DISALLOW_COPY_AND_ASSIGN(LanguageListFetcher);
   };
 
   // Callback function called when LanguageListFetcher::Request() is finished.
   void OnLanguageListFetchComplete(bool include_alpha_languages,
                                    bool success,
                                    const std::string& data);
 
   // Updates |all_supported_languages_| to contain the union of
   // |supported_languages_| and |supported_alpha_languages_|.
@@ skipping 13 matching lines @@
   // language list.
   scoped_ptr<LanguageListFetcher> language_list_fetcher_;
 
   // A LanguageListFetcher instance to fetch a server providing supported alpha
   // language list.
   scoped_ptr<LanguageListFetcher> alpha_language_list_fetcher_;
 
   // The last-updated time when the language list is sent.
   base::Time last_updated_;
 
+  // Helper class to know if it's allowed to make network resource requests.
+  ResourceRequestAllowedNotifier resource_request_allowed_notifier_;
+
   DISALLOW_COPY_AND_ASSIGN(TranslateLanguageList);
 };
 
 #endif  // CHROME_BROWSER_TRANSLATE_TRANSLATE_LANGUAGE_LIST_H_