Implement a salt for MediaSource IDs that can be cleared by a user.

chrome/browser/profiles/profile_io_data.cc

 // Copyright (c) 2012 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.
 
 #include "chrome/browser/profiles/profile_io_data.h"
 
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/bind.h"
@@ skipping 17 matching lines @@
 #include "chrome/browser/content_settings/host_content_settings_map.h"
 #include "chrome/browser/custom_handlers/protocol_handler_registry.h"
 #include "chrome/browser/custom_handlers/protocol_handler_registry_factory.h"
 #include "chrome/browser/download/download_service.h"
 #include "chrome/browser/download/download_service_factory.h"
 #include "chrome/browser/extensions/extension_info_map.h"
 #include "chrome/browser/extensions/extension_protocols.h"
 #include "chrome/browser/extensions/extension_resource_protocols.h"
 #include "chrome/browser/extensions/extension_system.h"
 #include "chrome/browser/io_thread.h"
+#include "chrome/browser/media/media_device_id_salt.h"
 #include "chrome/browser/net/about_protocol_handler.h"
 #include "chrome/browser/net/chrome_cookie_notification_details.h"
 #include "chrome/browser/net/chrome_fraudulent_certificate_reporter.h"
 #include "chrome/browser/net/chrome_http_user_agent_settings.h"
 #include "chrome/browser/net/chrome_net_log.h"
 #include "chrome/browser/net/chrome_network_delegate.h"
 #include "chrome/browser/net/evicted_domain_cookie_counter.h"
 #include "chrome/browser/net/load_time_stats.h"
 #include "chrome/browser/net/proxy_service_factory.h"
 #include "chrome/browser/net/resource_prefetch_predictor_observer.h"
@@ skipping 260 matching lines @@
       &enable_do_not_track_,
       &force_safesearch_,
       pref_service);
 
   scoped_refptr<base::MessageLoopProxy> io_message_loop_proxy =
       BrowserThread::GetMessageLoopProxyForThread(BrowserThread::IO);
 #if defined(ENABLE_PRINTING)
   printing_enabled_.Init(prefs::kPrintingEnabled, pref_service);
   printing_enabled_.MoveToThread(io_message_loop_proxy);
 #endif
+
   chrome_http_user_agent_settings_.reset(
       new ChromeHttpUserAgentSettings(pref_service));
 
   // These members are used only for one click sign in, which is not enabled
   // in incognito mode.  So no need to initialize them.
   if (!is_incognito()) {
     signin_names_.reset(new SigninNamesOnIOThread());
 
     google_services_username_.Init(
         prefs::kGoogleServicesUsername, pref_service);
@@ skipping 11 matching lines @@
         prefs::kReverseAutologinRejectedEmailList, pref_service);
     one_click_signin_rejected_email_list_.MoveToThread(io_message_loop_proxy);
 
     sync_disabled_.Init(prefs::kSyncManaged, pref_service);
     sync_disabled_.MoveToThread(io_message_loop_proxy);
 
     signin_allowed_.Init(prefs::kSigninAllowed, pref_service);
     signin_allowed_.MoveToThread(io_message_loop_proxy);
   }
 
+  media_device_id_salt_.reset(new MediaDeviceIDSalt(pref_service,
+                                                    is_incognito()));
+
   // The URLBlacklistManager has to be created on the UI thread to register
   // observers of |pref_service|, and it also has to clean up on
   // ShutdownOnUIThread to release these observers on the right thread.
   // Don't pass it in |profile_params_| to make sure it is correctly cleaned up,
   // in particular when this ProfileIOData isn't |initialized_| during deletion.
 #if defined(ENABLE_CONFIGURATION_POLICY)
   url_blacklist_manager_.reset(new policy::URLBlacklistManager(pref_service));
 #endif
 
   initialized_on_UI_thread_ = true;
@@ skipping 279 matching lines @@
   return host_content_settings_map_.get();
 }
 
 #if defined(ENABLE_NOTIFICATIONS)
 DesktopNotificationService* ProfileIOData::GetNotificationService() const {
   DCHECK(initialized_);
   return notification_service_;
 }
 #endif
 
+std::string ProfileIOData::GetMediaDeviceIDSalt() const {
+  return media_device_id_salt_->GetSalt();
+}
+
 void ProfileIOData::InitializeMetricsEnabledStateOnUIThread() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 #if defined(OS_CHROMEOS)
   // Just fetch the value from ChromeOS' settings while we're on the UI thread.
   // TODO(stevet): For now, this value is only set on profile initialization.
   // We will want to do something similar to the PrefMember method below in the
   // future to more accurately capture this state.
   chromeos::CrosSettings::Get()->GetBoolean(chromeos::kStatsReportingPref,
                                             &enable_metrics_);
 #elif defined(OS_ANDROID)
@@ skipping 76 matching lines @@
 
 bool ProfileIOData::ResourceContext::AllowContentAccess(
     const GURL& origin, ContentSettingsType type) {
   HostContentSettingsMap* content_settings =
       io_data_->GetHostContentSettingsMap();
   ContentSetting setting = content_settings->GetContentSetting(
       origin, origin, type, NO_RESOURCE_IDENTIFIER);
   return setting == CONTENT_SETTING_ALLOW;
 }
 
+std::string ProfileIOData::ResourceContext::GetMediaDeviceIDSalt() {
+  return io_data_->GetMediaDeviceIDSalt();
+}
+
 // static
 std::string ProfileIOData::GetSSLSessionCacheShard() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
   // The SSL session cache is partitioned by setting a string. This returns a
   // unique string to partition the SSL session cache. Each time we create a
   // new profile, we'll get a fresh SSL session cache which is separate from
   // the other profiles.
   static unsigned ssl_session_cache_instance = 0;
   return base::StringPrintf("profile/%u", ssl_session_cache_instance++);
 }
@@ skipping 184 matching lines @@
   enable_referrers_.Destroy();
   enable_do_not_track_.Destroy();
   force_safesearch_.Destroy();
 #if !defined(OS_CHROMEOS)
   enable_metrics_.Destroy();
 #endif
   safe_browsing_enabled_.Destroy();
   printing_enabled_.Destroy();
   sync_disabled_.Destroy();
   signin_allowed_.Destroy();
+  media_device_id_salt_.reset(NULL);

[Jói, 2013/11/04 16:53:29]

I'm not sure this is correct (destroying it on the UI thread). I would suggest
moving ownership of MediaDeviceIDSalt to the ResourceContext object since that's
where it's used from. You could just add an is_incognito parameter to the
constructor of ResourceContext.

[perkj_chrome, 2013/11/04 19:05:38]

This is as the same as the other objects and ensures that the objects are
created and destroyed on the UI thread if I understand this correct.
 If I move the ownership I get problem that I need the  the PrefService. I can
of course add  InitializeOnUIThread(Profile* profile) on the resource context as
well but MediaDeviceIdSalt::media_device_id_salt_ (StringPrefMember) must be
destroyed on the UI thread... So in that case I need to add a 
ShutdownOnUIThread() as well on the resource context... All in all it seems
better to me to keep this? Wdyt?  

[Jói, 2013/11/04 19:24:15]

I see now from the ProfileIOData documentation that Profile will make sure to
destroy ProfileIOData on the IO thread. So either approach is fine.

[willchan no longer on Chromium, 2013/11/04 19:33:00]

Sorry, I missed this. Just to doublecheck, what thread *should* this
MediaDeviceIDSalt be used on? IO thread? If so, it should *not* be destroyed
here. This function is for objects that need 2-phase shutdown (initiate shutdown
on UI thread, and then it gets deleted on the IO thread). You're actually doing
a delete on the UI thread. If this object is used on the IO thread, then this is
wrong and will lead to a use after free.

   session_startup_pref_.Destroy();
 #if defined(ENABLE_CONFIGURATION_POLICY)
   if (url_blacklist_manager_)
     url_blacklist_manager_->ShutdownOnUIThread();
 #endif
   if (chrome_http_user_agent_settings_)
     chrome_http_user_agent_settings_->CleanupOnUIThread();
   bool posted = BrowserThread::DeleteSoon(BrowserThread::IO, FROM_HERE, this);
   if (!posted)
     delete this;
@@ skipping 34 matching lines @@
 void ProfileIOData::SetCookieSettingsForTesting(
     CookieSettings* cookie_settings) {
   DCHECK(!cookie_settings_.get());
   cookie_settings_ = cookie_settings;
 }
 
 void ProfileIOData::set_signin_names_for_testing(
     SigninNamesOnIOThread* signin_names) {
   signin_names_.reset(signin_names);
 }