Make default media device ID salts random by default

chrome/browser/profiles/profile_io_data.cc

Index: chrome/browser/profiles/profile_io_data.cc
diff --git a/chrome/browser/profiles/profile_io_data.cc b/chrome/browser/profiles/profile_io_data.cc
index 11c06609c13b0d6c625f2246853ebf6ea48610b1..cbbfef26a9af9c6df78d953b35dcc3d166dd797e 100644
--- a/chrome/browser/profiles/profile_io_data.cc
+++ b/chrome/browser/profiles/profile_io_data.cc
@@ -504,7 +504,8 @@ void ProfileIOData::InitializeOnUIThread(Profile* profile) {
                             local_state_pref_service);
   quick_check_enabled_.MoveToThread(io_task_runner);
 
-  media_device_id_salt_ = new MediaDeviceIDSalt(pref_service, IsOffTheRecord());
+  if (!IsOffTheRecord())
+    media_device_id_salt_ = new MediaDeviceIDSalt(pref_service);
 
   network_prediction_options_.Init(prefs::kNetworkPredictionOptions,
                                    pref_service);
@@ -871,6 +872,7 @@ HostContentSettingsMap* ProfileIOData::GetHostContentSettingsMap() const {
 }
 
 ResourceContext::SaltCallback ProfileIOData::GetMediaDeviceIDSalt() const {
+  DCHECK(media_device_id_salt_);
   return base::Bind(&MediaDeviceIDSalt::GetSalt, media_device_id_salt_);
 }
 
@@ -1010,7 +1012,10 @@ void ProfileIOData::ResourceContext::CreateKeygenHandler(
 
 ResourceContext::SaltCallback
 ProfileIOData::ResourceContext::GetMediaDeviceIDSalt() {
-  return io_data_->GetMediaDeviceIDSalt();
+  if (io_data_->HasMediaDeviceIDSalt())
+    return io_data_->GetMediaDeviceIDSalt();
+
+  return content::ResourceContext::GetMediaDeviceIDSalt();
 }
 
 void ProfileIOData::Init(