No Issue - Implement crypto.randomUUID

We already have code in the platform to generate random UUIDs. This simply exposes that functionality via the crypto.UUID function

dom/base/Crypto.cpp

@@ -115,6 +115,27 @@ Crypto::GetRandomValues(JSContext* aCx, const ArrayBufferView& aArray,
   aRetval.set(view);
 }
 
+void Crypto::RandomUUID(nsAString& aRetVal)
+{
+  // NSID_LENGTH == 39 == 36 UUID chars + 2 curly braces + 1 NUL byte
+  static_assert(NSID_LENGTH == 39);
+
+  nsCOMPtr<nsIUUIDGenerator> uuidgen =
+    do_GetService("@mozilla.org/uuid-generator;1");
+
+  nsID uuid;
+
+  nsresult rv = uuidgen->GenerateUUIDInPlace(&uuid);
+
+  char uuidBuffer[NSID_LENGTH]; 
+  uuid.ToProvidedString(uuidBuffer);
+
+  nsCString asciiString(uuidBuffer);
+
+  // Convert UUID chars to UTF-16 retval, omitting the curly braces and NUL
+  CopyASCIItoUTF16(Substring(asciiString, 1, NSID_LENGTH - 3), aRetVal);
+}
+
 SubtleCrypto*
 Crypto::Subtle()
 {

dom/base/Crypto.h

@@ -9,6 +9,7 @@
 #include "mozilla/dom/SubtleCrypto.h"
 #include "nsIGlobalObject.h"
 
+#include "nsString.h"
 #include "nsWrapperCache.h"
 #include "mozilla/dom/TypedArray.h"
 #define NS_DOMCRYPTO_CID \
@@ -39,6 +40,8 @@ public:
                   JS::MutableHandle<JSObject*> aRetval,
                   ErrorResult& aRv);
 
+void RandomUUID(nsAString& aRetVal);
+
   SubtleCrypto*
   Subtle();
 

dom/webidl/Crypto.webidl

@@ -18,4 +18,7 @@ interface Crypto {
 
   [Throws]
   ArrayBufferView getRandomValues(ArrayBufferView array);
+
+  [SecureContext]
+  DOMString randomUUID();
 };