Update CM API IDL to use SecureContext

chrome/browser/flag_descriptions.cc

Index: chrome/browser/flag_descriptions.cc
diff --git a/chrome/browser/flag_descriptions.cc b/chrome/browser/flag_descriptions.cc
index 80650dcaa03df16f3f22dba2d8b9281e72b1ab7c..7e4d9de1a1916ae998066ac40480150b719724fa 100644
--- a/chrome/browser/flag_descriptions.cc
+++ b/chrome/browser/flag_descriptions.cc
@@ -929,12 +929,6 @@ const char kPinchScaleName[] = "Pinch scale";
 const char kPinchScaleDescription[] =
     "Enables experimental support for scale using pinch.";
 
-const char kCredentialManagerApiName[] = "Experimental Credential Manager API";
-
-const char kCredentialManagerApiDescription[] =
-    "Enables an experimental implementation of the Credential Manager API. "
-    "Don't enable this unless you know what you're doing.";
-
 const char kReducedReferrerGranularityName[] =
     "Reduce default 'referer' header granularity.";