Update scopes parameter in GetAuthToken callback

Previously, the documentation for the scopes parameter was lacking and
the callback parameter name did not fully reflect its purpose. This CL
renames the parameter to be more descriptive and adds additional
documentation.

Bug: 1100535
Change-Id: I6001d36a7701c6484f318fb6e983f1ef933da14f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2354525Reviewed-by: Devlin <rdevlin.cronin@chromium.org>
Reviewed-by: Alex Ilin <alexilin@chromium.org>
Commit-Queue: William Lin <williamlin@google.com>
Cr-Commit-Position: refs/heads/master@{#798314}

chrome/common/extensions/api/identity.idl

@@ -85,7 +85,7 @@ namespace identity {
   };
 
   callback GetAuthTokenCallback = void (optional DOMString token,
-                                        optional DOMString[] scopes);
+                                        optional DOMString[] grantedScopes);
   callback GetAccountsCallback = void (AccountInfo[] accounts);
   callback GetProfileUserInfoCallback = void (ProfileUserInfo userInfo);
   callback InvalidateAuthTokenCallback = void ();
@@ -116,9 +116,11 @@ namespace identity {
     //
     // |details| : Token options.
     // |callback| : Called with an OAuth2 access token as specified by the
-    // manifest, or undefined if there was an error. The <code>scopes</code>
-    // parameter is not yet available. It will be populated in future versions
-    // of Chrome.
+    // manifest, or undefined if there was an error. The
+    // <code>grantedScopes</code> parameter is not yet available and will be
+    // populated in future versions of Chrome. When available, this parameter
+    // will contain the list of granted scopes corresponding with the returned
+    // token.
     static void getAuthToken(optional TokenDetails details,
                              optional GetAuthTokenCallback callback);