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      1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef CHROME_BROWSER_WEB_RESOURCE_WEB_RESOURCE_SERVICE_H_
      6 #define CHROME_BROWSER_WEB_RESOURCE_WEB_RESOURCE_SERVICE_H_
      7 
      8 #include <string>
      9 
     10 #include "base/memory/ref_counted.h"
     11 #include "base/memory/scoped_ptr.h"
     12 #include "base/memory/weak_ptr.h"
     13 #include "chrome/browser/web_resource/json_asynchronous_unpacker.h"
     14 #include "chrome/browser/web_resource/resource_request_allowed_notifier.h"
     15 #include "net/url_request/url_fetcher_delegate.h"
     16 #include "url/gurl.h"
     17 
     18 class PrefService;
     19 
     20 namespace base {
     21 class DictionaryValue;
     22 }
     23 
     24 namespace net {
     25 class URLFetcher;
     26 }
     27 
     28 // A WebResourceService fetches JSON data from a web server and periodically
     29 // refreshes it.
     30 class WebResourceService
     31     : public net::URLFetcherDelegate,
     32       public JSONAsynchronousUnpackerDelegate,
     33       public base::RefCountedThreadSafe<WebResourceService>,
     34       public ResourceRequestAllowedNotifier::Observer {
     35  public:
     36   WebResourceService(PrefService* prefs,
     37                      const GURL& web_resource_server,
     38                      bool apply_locale_to_url_,
     39                      const char* last_update_time_pref_name,
     40                      int start_fetch_delay_ms,
     41                      int cache_update_delay_ms);
     42 
     43   // Sleep until cache needs to be updated, but always for at least
     44   // |start_fetch_delay_ms| so we don't interfere with startup.
     45   // Then begin updating resources.
     46   void StartAfterDelay();
     47 
     48   // JSONAsynchronousUnpackerDelegate methods.
     49   virtual void OnUnpackFinished(
     50       const base::DictionaryValue& parsed_json) OVERRIDE;
     51   virtual void OnUnpackError(const std::string& error_message) OVERRIDE;
     52 
     53  protected:
     54   virtual ~WebResourceService();
     55 
     56   // For the subclasses to process the result of a fetch.
     57   virtual void Unpack(const base::DictionaryValue& parsed_json) = 0;
     58 
     59   PrefService* prefs_;
     60 
     61  private:
     62   class UnpackerClient;
     63   friend class base::RefCountedThreadSafe<WebResourceService>;
     64 
     65   // net::URLFetcherDelegate implementation:
     66   virtual void OnURLFetchComplete(const net::URLFetcher* source) OVERRIDE;
     67 
     68   // Schedules a fetch after |delay_ms| milliseconds.
     69   void ScheduleFetch(int64 delay_ms);
     70 
     71   // Starts fetching data from the server.
     72   void StartFetch();
     73 
     74   // Set |in_fetch_| to false, clean up temp directories (in the future).
     75   void EndFetch();
     76 
     77   // Implements ResourceRequestAllowedNotifier::Observer.
     78   virtual void OnResourceRequestsAllowed() OVERRIDE;
     79 
     80   // Helper class used to tell this service if it's allowed to make network
     81   // resource requests.
     82   ResourceRequestAllowedNotifier resource_request_allowed_notifier_;
     83 
     84   // The tool that fetches the url data from the server.
     85   scoped_ptr<net::URLFetcher> url_fetcher_;
     86 
     87   // The tool that parses and transforms the json data. Weak reference as it
     88   // deletes itself once the unpack is done.
     89   JSONAsynchronousUnpacker* json_unpacker_;
     90 
     91   // True if we are currently fetching or unpacking data. If we are asked to
     92   // start a fetch when we are still fetching resource data, schedule another
     93   // one in |cache_update_delay_ms_| time, and silently exit.
     94   bool in_fetch_;
     95 
     96   // URL that hosts the web resource.
     97   GURL web_resource_server_;
     98 
     99   // Indicates whether we should append locale to the web resource server URL.
    100   bool apply_locale_to_url_;
    101 
    102   // Pref name to store the last update's time.
    103   const char* last_update_time_pref_name_;
    104 
    105   // Delay on first fetch so we don't interfere with startup.
    106   int start_fetch_delay_ms_;
    107 
    108   // Delay between calls to update the web resource cache. This delay may be
    109   // different for different builds of Chrome.
    110   int cache_update_delay_ms_;
    111 
    112   // So that we can delay our start so as not to affect start-up time; also,
    113   // so that we can schedule future cache updates.
    114   base::WeakPtrFactory<WebResourceService> weak_ptr_factory_;
    115 
    116   DISALLOW_COPY_AND_ASSIGN(WebResourceService);
    117 };
    118 
    119 #endif  // CHROME_BROWSER_WEB_RESOURCE_WEB_RESOURCE_SERVICE_H_
    120