chrome/browser/chromeos/extensions/external_pref_cache_loader.cc

   1 // Copyright (c) 2013 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 #include "chrome/browser/chromeos/extensions/external_pref_cache_loader.h"
   6
   7 #include "base/bind.h"
   8 #include "base/bind_helpers.h"
   9 #include "base/memory/singleton.h"
  10 #include "base/observer_list.h"
  11 #include "base/values.h"
  12 #include "chrome/browser/browser_process.h"
  13 #include "chrome/browser/chromeos/extensions/external_cache.h"
  14 #include "content/public/browser/browser_thread.h"
  15
  16 namespace chromeos {
  17
  18 namespace {
  19
  20 // Directory where the extensions are cached.
  21 const char kPreinstalledAppsCacheDir[] = "/var/cache/external_cache";
  22
  23 // Singleton class that holds ExternalCache and dispatches cache update events
  24 // to per-profile instances of ExternalPrefCacheLoader. This multiplexing
  25 // is required for multi-profile case.
  26 class ExternalCacheDispatcher : public ExternalCache::Delegate {
  27  public:
  28   static ExternalCacheDispatcher* GetInstance() {
  29     return Singleton<ExternalCacheDispatcher>::get();
  30   }
  31
  32   // Implementation of ExternalCache::Delegate:
  33   virtual void OnExtensionListsUpdated(
  34       const base::DictionaryValue* prefs) OVERRIDE {
  35     is_extensions_list_ready_ = true;
  36     FOR_EACH_OBSERVER(ExternalPrefCacheLoader, pref_loaders_,
  37                       OnExtensionListsUpdated(prefs));
  38   }
  39
  40   void UpdateExtensionsList(scoped_ptr<base::DictionaryValue> prefs) {
  41     DCHECK(!is_extensions_list_ready_);
  42     external_cache_.UpdateExtensionsList(prefs.Pass());
  43   }
  44
  45   // Return false if cache doesn't have list of extensions and it needs to
  46   // be provided via UpdateExtensionsList.
  47   bool RegisterExternalPrefCacheLoader(ExternalPrefCacheLoader* observer,
  48                                        int base_path_id) {
  49     pref_loaders_.AddObserver(observer);
  50
  51     if (base_path_id_ == 0) {
  52       // First ExternalPrefCacheLoader is registered.
  53       base_path_id_ = base_path_id;
  54       return false;
  55     } else {
  56       CHECK_EQ(base_path_id_, base_path_id);
  57       if (is_extensions_list_ready_) {
  58         // If list of extensions is not ready, |observer| will be notified later
  59         // in OnExtensionListsUpdated.
  60         observer->OnExtensionListsUpdated(external_cache_.cached_extensions());
  61       }
  62       return true;
  63     }
  64   }
  65
  66   void UnregisterExternalPrefCacheLoader(ExternalPrefCacheLoader* observer) {
  67     pref_loaders_.RemoveObserver(observer);
  68   }
  69
  70  private:
  71   friend struct DefaultSingletonTraits<ExternalCacheDispatcher>;
  72
  73   ExternalCacheDispatcher()
  74     : external_cache_(kPreinstalledAppsCacheDir,
  75                       g_browser_process->system_request_context(), this, true),
  76       base_path_id_(0),
  77       is_extensions_list_ready_(false) {
  78   }
  79
  80   ExternalCache external_cache_;
  81   ObserverList<ExternalPrefCacheLoader> pref_loaders_;
  82   int base_path_id_;
  83   bool is_extensions_list_ready_;
  84
  85   DISALLOW_COPY_AND_ASSIGN(ExternalCacheDispatcher);
  86 };
  87
  88 }  // namespace
  89
  90 ExternalPrefCacheLoader::ExternalPrefCacheLoader(int base_path_id)
  91   : ExternalPrefLoader(base_path_id, ExternalPrefLoader::NONE) {
  92 }
  93
  94 ExternalPrefCacheLoader::~ExternalPrefCacheLoader() {
  95   ExternalCacheDispatcher::GetInstance()->UnregisterExternalPrefCacheLoader(
  96       this);
  97 }
  98
  99 void ExternalPrefCacheLoader::OnExtensionListsUpdated(
 100     const base::DictionaryValue* prefs) {
 101   prefs_.reset(prefs->DeepCopy());
 102   ExternalPrefLoader::LoadFinished();
 103 }
 104
 105 void ExternalPrefCacheLoader::StartLoading() {
 106   if (!ExternalCacheDispatcher::GetInstance()->RegisterExternalPrefCacheLoader(
 107           this, base_path_id_)) {
 108     // ExternalCacheDispatcher doesn't know list of extensions load it.
 109     ExternalPrefLoader::StartLoading();
 110   }
 111 }
 112
 113 void ExternalPrefCacheLoader::LoadFinished() {
 114   ExternalCacheDispatcher::GetInstance()->UpdateExtensionsList(prefs_.Pass());
 115 }
 116
 117 }  // namespace chromeos