Make default media device ID salts random by default

content/public/browser/resource_context.h

Index: content/public/browser/resource_context.h
diff --git a/content/public/browser/resource_context.h b/content/public/browser/resource_context.h
index 039ad94006ded4e49f25ad2a3784d3ed9d7e6b40..73b3aa55fdcd6702040cbf3f76934af455e8bb05 100644
--- a/content/public/browser/resource_context.h
+++ b/content/public/browser/resource_context.h
@@ -77,6 +77,10 @@ class CONTENT_EXPORT ResourceContext : public base::SupportsUserData {
   // fixed.
   typedef base::Callback<std::string()> SaltCallback;
   virtual SaltCallback GetMediaDeviceIDSalt();
+
+  // Utility functions useful for implementations
+  static std::string CreateRandomMediaDeviceIDSalt();
+  static SaltCallback CreateSaltCallback(const std::string& salt);
 };
 
 }  // namespace content