Add the Mojo implementation of authenticator.mojom's MakeCredential.

content/public/common/content_features.cc

Index: content/public/common/content_features.cc
diff --git a/content/public/common/content_features.cc b/content/public/common/content_features.cc
index 4a1d40e83a760fc089824a470558320758b2f50e..e04398705b6f75ec1a7020b336c517b967b3af93 100644
--- a/content/public/common/content_features.cc
+++ b/content/public/common/content_features.cc
@@ -243,6 +243,11 @@ const base::Feature kVrShell{"VrShell", base::FEATURE_DISABLED_BY_DEFAULT};
 const base::Feature kWebAssembly{"WebAssembly",
                                  base::FEATURE_DISABLED_BY_DEFAULT};
 
+// Controls whether the WebAuthentication API is enabled:
+// https://w3c.github.io/webauthn
+const base::Feature kWebAuth{"WebAuthentication",
+                             base::FEATURE_DISABLED_BY_DEFAULT};
+
 // If WebGL Image Chromium is allowed, this feature controls whether it is
 // enabled.
 const base::Feature kWebGLImageChromium{"WebGLImageChromium",