Make default media device ID salts random by default

chrome/browser/extensions/api/webrtc_audio_private/webrtc_audio_private_api.h

Index: chrome/browser/extensions/api/webrtc_audio_private/webrtc_audio_private_api.h
diff --git a/chrome/browser/extensions/api/webrtc_audio_private/webrtc_audio_private_api.h b/chrome/browser/extensions/api/webrtc_audio_private/webrtc_audio_private_api.h
index a90c4aa39eeb933d943e713536249378cc5f4a70..e10607993d80d1fc8898013726e1c2f2447d093e 100644
--- a/chrome/browser/extensions/api/webrtc_audio_private/webrtc_audio_private_api.h
+++ b/chrome/browser/extensions/api/webrtc_audio_private/webrtc_audio_private_api.h
@@ -7,6 +7,8 @@
 
 #include <stddef.h>
 
+#include <string>
+
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/system_monitor/system_monitor.h"
@@ -96,10 +98,10 @@ class WebrtcAudioPrivateFunction : public ChromeAsyncExtensionFunction {
 
   // Callable from any thread. Must previously have called
   // |InitDeviceIDSalt()|.
-  const content::ResourceContext::SaltCallback& device_id_salt() const;
+  std::string device_id_salt() const;
 
  private:
-  content::ResourceContext::SaltCallback device_id_salt_;
+  std::string device_id_salt_;
 
   DISALLOW_COPY_AND_ASSIGN(WebrtcAudioPrivateFunction);
 };